This dissertation has been microfilmed exactly as received 67—16,286 HASELTON, George Montgomery, 1928- GLACIAL GEOLOGY OF MUIR INLET, SOUTHEASTERN ALASKA,
The Ohio State University, Ph.D., 1967 Geology
University Microfilms, Inc., Ann Arbor, Michigan GLACIAL GEOLOGY OF MUIR INLET, SOUTHEASTERN ALASKA
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Graduate School of The Ohio State University
by
George M, Haselton, B.A., M.A.
The Ohio State University 1 9 6 7
Approved by
Adviser Department of Geology ACKNOWLEDGEMENTS
This report is based on field work for the National Science
Foundation during the summers of 1963 and 1964. The author is most grateful to the National Science Foundation for their generous support of th is study under Grants GP-1058 and GP-2537, which were awarded to
The Ohio S tate U niversity Research Foundation as P ro jec ts RF-1639 and
RF-1813, and for permission to use the results of the study for this dissertation. It is a pleasure to acknowledge the friendly advice and help of Dr. R, P. Goldthwait, Professor and Chairman of the Department of Geology at The Ohio State University, under whose direction the field project was begun. His encouragement, counsel, and friendly guidance both in the field and during the preparation of this dissertation are gratefully appreciated.
Special thanks are due to the U.S. National Park Service for generous logistical support, particularly in transportation of men and supplies to and from the fie ld , and in communications. The help and support of Mr. L. J. Mitchell, then Superintendent of Glacier Bay and
Sitka National Monuments, Messrs. John Fisher, David Butts, Kenneth
Youmans, and Charles Janda, all of the Park Service staff at Bartlett
Cove, and Captain James Saunders and the crew of the Park Service motor vessel "Nunatak" are gratefully acknowledged.
i i Able assistance in the field was rendered by Messrs. Frederick
Larsen and Robert Whitelaw in 1963; Kenneth F itz p a tric k and Carl
Weiman in 1964.
The author is deeply indebted to Dr. W. 0, Field of the American
Geographical Society for his frequent correspondence, visit to the field area, and helpful suggestions, together with detailed photographic
coverage which helped to make this study successful.
The manuscript was carefully reviewed by Dr. R. P. Goldthwait,
Dr. G. E. Moore, and Dr. R. L. Bates.
The many hours of discussion and helpful suggestions of
Dr. Arthur Mirsky and Mr. Garry McKenzie of the Institute of Polar
Studies were of great help in refining and clarifying ideas presented by the author.
i i i To Dianne, without whose help this p ro ject would have been im possible.
iv AUTOBIOGRAPHY
I f George Montgomery H aselton, was born in W orcester, Massachu setts, on February 28, 1928. I received my primary and secondary school education in the public schools of Andover, Massachusetts. My undergraduate training was taken at Colby College, in Waterville,
Maine, from which I received the degree of Bachelor of Arts in 1951.
I received the degree of Master of Arts from Boston U niversity in 1958.
In 1962, I enrolled in the Graduate School of The Ohio State University where I specialized in the Department of Geology.
From April, 1962, until May, 1963, I held a National Science
Foundation Faculty Fellowship, From June, 1963, to June, 1964, while still in residence at The Ohio State University, I was a research assistant with The Ohio State University, Institute of Polar Studies.
From 1965, until completion of the requirements for the Doctor of Philosophy degree, I was a Graduate Teaching Assistant in the
Department of Geology at The Ohio State University. CONTENTS
PAGE
ACKNOWLEDGMENTS...... • ...... i i
VITA ...... V
TABLES...... ix
FIGURES...... X
INTRODUCTION ...... 1
Purpose ...... 1
L ocation ...... 1
Physiographic Setting ...... 1
C lim a te ...... 5
W in d ...... 8
Temperature ...... 8
C lo u d in e s s ...... 11
Precipitation ...... 11
PREVIOUS INVESTIGATIONS...... 14
GEOLOGIC SETTING...... 27
G e n e r a l ...... 27
Sedimentary Rocks ...... 27
Intrusive Rocks ...... 32
Age of Plutonic Granitic Rocks ...... 34
Dike Rocks ...... 35
Volcanic Rocks ...... 36
Metasedimentary Rocks ...... 39 vi CONTENTS (Continued)
PAGE
Carbonate Rocks ...... 40
Ore M inerals ...... 42
Brief Geologic History...... 43
GLACIAL STRATIGRAPHY ...... 44
G e n e r a l ...... 44
Late Wisconsin Strata ...... 54
Basal T i l l ...... 54
Forest Creek Formation ...... 54
Muir F o rm atio n ...... 60
Van Horn Formation ...... '...... 67
Hypsithermal--Lower Member of the Van Horn Formation . 74
Early Neoglacial--Middle Member of the Van Horn F o rm atio n ...... 77
Middle Neoglacial--Upper Member of the Van Horn F o rm atio n ...... 89
Glacier Bay Formation ...... 92
Seal River Formation ...... 99
FEATURES OF NEOGLACIAL IC E ...... _...... 103
Till Fabric ...... 103
Streamline Glacial Forms ...... 107
Grooved T ill and Gravel ...... 107
Drumlins » ...... I ll
Crag-and-Tail Features ...... I ll
S tria e ...... 116
Thickness of Neoglacial I c e ...... 116
vii CONTENTS (Continued)
PAGE
DEGLACIATION OF THE McBRIDE REMNANT AREA...... 125
Wasting of the McBride Remnant Ice ...... 125
Rates of Ice Wastage ...... 125
Drainage Changes During Deglaciation ...... 128
Marginal Drainage Channels ...... 130
Eskers...... 133
Karnes ...... 140
Residual Movement of Remnant Ice ...... 142
Minor T ill R id g e s ...... 144
Crevasse Fillings ...... 144
Shear Plane Ridges ...... 152
Ice Disintegration Ridges ...... 155
Theories for Ridge Development ...... 157
GLACIAL HISTORY...... 161
SUMMARY...... 176
APPENDIXES
APPENDIX I. PEBBLE COUNT LITHOLOGIES...... 182
APPENDIX II. METEOROLOGICAL DATA...... 192
APPENDIX I I I . MECHANICAL ANALYSES AND CUMULATIVE CURVES OF LAKE SILTS, TILLS, AND GRAVELS...... 207
BIBLIOGRAPHY ...... 220
viii TABLES
TABLE PAGE
1. Mean monthly maximum and minimum tem peratures (®C) at Nunatak Cove and Juneau for July-August, 1963-1964. . . . 9
2. Monthly maximum, minimum, and mean tem peratures (°C) at Nunatak Cove and B a rtle tt Cove, 1963-1964 seasons .... 10
3. Total monthly rainfall at Bartlett Cove and Nunatak Cove, 1963-1964 seasons ...... 12
4. Average pebble lithologies of the Muir Formation, Glacier Bay Formation, ablation till, Van Horn Formation, and modern outwash ...... 64
5. Radiocarbon dates from sh e lls and wood in the Forest Creek Formation, Van Horn Formation, and Glacier Bay F o rm a tio n ...... 71
6. Radiocarbon dates on wood above and below lacustrine deposits of the middle member of the Van Horn F o rm a tio n ...... 84
7. Pebble counts of the Muir Inlet area ...... 183
8. Meteorological data at Nunatak Cove ...... 193
9. Meteorological data at Bartlett Cove...... 199
10. Meteorological data for Gustavus, Alaska, 1951-1960 .... 205
11. Mechanical composition of lacustrine silts ...... 209
12. Mechanical composition of t i l l s and g ra v e l ...... 217
ix FIGURES
FIGURE ' PAGE
1. G lacier Bay National Monument, Alaska ...... 2
2. Maximum and minimum temperatures at Nunatak Cove for the 1963 and 1964 seasons ...... 6
3. Rainfall at Nunatak Cove for the 1963 and 1964 seasons . . 7
4. Geologic map and ice position map of the Muir Glacier Basin in 1890. Compiled by H. P. Cushing ...... 16
5. Map of Glacier Bay and Muir Inlet (1890-1892) by H. F. Reid, et al ...... 17
6. Muir Inlet, Glacier Bay National Monument, Alaska ...... 19
7. Map of Muir Inlet region showing retreat of glacier fronts by decades since 1880 ...... 22
8. Air photograph of Upper Muir I n l e t ...... 24
9. Air photograph of Upper Muir In le t ...... 25
10. Generalized geologic map of Upper Muir I n l e t ...... 28
11. Frost shattered dike rock ...... 37
12. S tratigraphie section of formations in Upper Muir In le t. . 45
13. Correlation diagrams of stratigraphie sections Nos. 1-9. . 46
14. Correlation diagrams of stratigraphie sections Nos. 1 0 - 1 8 ...... 48
15. Correlation diagrams of stratigraphie sections Nos. 1 9 - 2 4 ...... 50
16. Detailed stratigraphie relationships between Canyon Creek and North Creek ...... 52
17. Map showing location of sections' of Figures 13-16 ...... 53
18. Forest Creek Gorge ...... 55 FIGURES (Continued)
FIGURE PAGE
19. "The Nunatak"...... 62
20. Stratigraphy at Two-Till Creek ...... 63
21. Mechanical composition of tills and gravel ...... 65
22. S tratigraphy at Canyon Creek ...... 68
23. S tratigraphy at Canyon Creek ...... 69
* * 24, Forest horizons in the upper gravel member of the Van Horn F o rm a tio n ...... 76
25, Graded bedding at Two-Till Creek ...... 78
26, Lacustrine sediments at Nunatak Cove ...... 80
27, Mechanical composition of lacustrine silts ...... 81
28, Upper gravel member of the Van Horn Formation ...... 90
29, Cross bedding in gravel ...... 90
30, Upper Van Horn gravel a t Fault C r e e k ...... 91
31, Collapsed structure in Upper Van Horn sands ...... 91
32, Stratigraphy on north side of Minnesota Ridge ...... 93
33, Stratigraphy at Forest Creek ...... 93
34, Stratigraphy at Larsen Creek ...... 95
35, Erosion in an unvegetated a r e a ...... 96
36, Erosion in an unvegetated area ...... 96
37, Seal River outwash ...... 101
38, Ablation debris ...... 102
39, Directional features related to Neoglacial ice, Muir I n le t ...... 104
40, Fabric analyses of Glacier Bay Formation (Till) ...... 105
41, Crag-and-Tail features ...... 108
xi FIGURES (Continued)
FIGURE PAGE
42. Drumlinized topography, McBride Remnant area ...... 109
43. Drumlinized topography, Wachusett Inlet region ...... 109
44. Plane-table map of crevasse filling ridges and crag -an d -tail ridges ...... 112
45. Panorama of Muir Glacier system, 1892 ...... 118
46. Panorama of Upper Muir In le t, 1929 ...... 120
47. Panorama of McBride Remnant area, 1950 ...... 122
48. Plane-table map of ice-contact features ...... 124
49. Downwasting McBride Remnant ice, 1963...... 127
50. Downwasting McBride Remnant ice, 1964 ...... 127
51. Goose Creek ...... 129
52. Abandoned McBride Remnant m eltwater channel ...... 129
53. Canyon Creek meltwater channel ...... 131
54. Successive meltwater channels outlining past ice p o s i t i o n ...... 131
55. Forest Creek delta ...... 132
56. Ice-cored esker a t McBride G lacier ...... 134
57. Ice-cored eskers and kames, McBride Remnantarea ...... 135
58. Ablation blanket around eskers ...... 135
59. Kettle-hole development in an esker ...... 136
60. Gravel esker between t i l l ridges near CanyonCreek .... 136
61. Englacial esker, Muir Remnant Glacier ...... 138
62. Englacial esker, Muir Remnant G la c ie r ...... 138
63. Dissected esker system south of CasementGlacier ...... 139
64. Boulderyesker southwest of Casement Glacier ...... 139
xii FIGURES (Continued)
FIGURE PAGE
65. Large ice-cored kame, east side McBride Remnant area . . . 141
66. Moulin-kame, Muir Remnant Glacier ...... 141
67. Kames on Burroughs Glacier ...... 143
68. Crevasse f illin g rid g es, McBride Remnant Valley ...... 145
69. Crevasse filling ridges and shear-plane-till ridges. . . . 145
70. Plane-table map of crevasse filling ridges east of "The Nunatak" ...... 146
71. Crevasse filling till ridges east of "The Nunatak" .... 147
72. Cross section of crevasse filling ridge ...... 149
73. Cross section of crevasse filling till ridge ...... 149
74. Small "squeeze-up" ridges (crevasse fillings) ...... 150
75. Large "squeeze-up" ridge ...... 150
76. Crevasse filling ridge being "squeezed up" ...... 151
77. Till released from "squeezç-up"...... 153
78. Close-up of till "squeeze-up" in shear ...... 153
79. T ill in shear on east side of McBride Remnant ic e ...... 154
80. Circular ice-disintegration ridges ...... 156
81. Circular ice-disintegration gravel ridges ...... 156
82. Map of glacial and postglacial features, Muir Inlet. . . . 158
83. Stumps, 7000 years o l d ...... 162
84. Remnant of climax fo rest ...... 162
85. Tree in growth position in gravel showing effect of stream abrasion ...... 164
86. Delta development at Goose Creek'...... 172
87. Delta developing at terminus of McBride Glacier ...... 172 x iii FIGURES (Continued)
FIGURE PAGE
88. Lake, west end of Plateau Glacier. 174
89. Muir Remnant G lacier ...... , 179
90. Maximum and minimum tem peratures a t B a r tle tt Cove for the seasons June-September, 1963-1964 ...... 197
91. Rainfall at Bartlett Cove for the seasons June- September, 1963-1964 ...... 198
92. Grain size distribution diagram, lacustrine silts. . 208
93. Grain size distribution diagram...... 210
94. Grain size di stribution diagram ...... 211
95. Grain size distribution diagram...... 212
96. Grain size distribution diagram...... 213
97. Grain size di stribution diagram...... 214
98. Grain size di stribution diagram...... 215
99. Grain size distribution diagram...... 216
XIV INTRODUCTION
Purpose
The purpose of the 1963 and 1964 fie ld in v estig atio n s was
(l) to study in detail the Pleistocene stratigraphy in the Muir Inlet
area as it relates to Late Wisconsin, Interstadial, and Neoglacial
times; (2) to examine ice contact, subglacial, and englacial features
in relation to the déglaciation of this area; (3) to use radiocarbon dating in determining the late glacial history of this area; and
(4 ) to make fabric studies of till to determine past ice motion, and pebble counts to determine possible source areas.
Location
Muir Inlet is in the northeastern corner of Glacier Bay
National Monument in southeastern Alaska. The region investigated lies between latitude 58** 52' and 59® 04' north, and between longitude
136® 00' and 136® 07* west. It is about 130 km northwest of Juneau and 48 km southwest of Haines (Fig. 1).
Physiographic Setting
By an act of Congress, the upper part of Glacier Bay became a
Na'tional Monument on February 26, 1925. It was enlarged in 1939 to
Include all of Glacier Bay and all the land between Glacier Bay and the Pacific Ocean (Fig. 1). Glacier Bay National Monument comprises an ' At Iwna
5^7000
B30(^ / (NMT.JFWPfWEÂTSâC VYOUNG *S *S \ ♦ TREE NT ,-+5720 3374 /
JUNEAU ICEFIELD
I BARTLETT Cat •HOE» ST*T « WSTWUS
I 1 MONUMENT BOUNDARY Jÿ E i ^ ELEVATION
R 5 3 ] STREAMS
20 MILES 2 0 KILOMETERS
FIGURE I. GLACIER BAY NATIONAL CHICHAGOF ISLAND MONUMENT, ALASKA I s tf 1137' area of about 8000 sq km. It is part of the rugged Coast-Range region of southeastern Alaska, and it contains several large tributary fjords.
Glacier Bay is a tributary to Icy Strait and is the largest water body
in the National Monument, being approximately 104 km long and 16 km wide
at its widest point. Northward it branches into several arms; Muir
In le t to the north and east and Queen, Rendu, Tarr, Johns Hopkins, and Geikie Inlets to the north and west (Fig. I). Southward, Glacier
Bay contains numerous islands composed of unconsolidated material and bedrock. Many glaciers still reach tidewater and many others are close to high tide line, as seen in Figure 1. Glacier Bay National Monument
is flanked on the east by the Chilkat Range and Takhinsha Mountains with maximum elevations of 2200 meters. These mountains form the drainage divide between the National Monument and Lynn Canal to the east. Névé fie ld s for the Muir, Riggs, McBride, and Casement G laciers are on the west side of this range. Elevations decrease southward, giving way to an extensive outwash plain that leads into Icy Strait.
The western tw o-thirds of G lacier Bay Monument is composed of deep fjords and high mountains of the Fairweather Range, which culminate in the 4673-meter peak of Mount Fairweather. The most extensive glaciers are in this region; some are advancing and many are tidal. Recent
surges have been reported on Tyeen, Rendu, Carroll, and La Perouse
Glaciers (Field, 1967), The Fairweather Range decreases in elevation southward and ends a t Cross Sound, The Brady G lacier, some 300 sq km in area, is the largest ice mass in the National Monument. It is a com plex piedmont-transection glacier, lying along the east side of the
Fairweather Range and separated from Glacier Bay by a lower range of 4 mountains whose highest elevation is about 1540 meters. The southern half of the Monument is less rugged, with low rounded peaks 600 to 900 meters high. These peaks are covered by a dense vegetation, which includes a climax forest of Sitka spruce (Picea sitchensis) and Western hemlock (Tsuga heterophylla), and an understory of deep mosses and devil's club (Oplopanax horridus). The regions near the head of the tributary inlets of Glacier Bay Monument are, for the most part, still scantily vegetated because of recent glacial retreat. In these head ward regions an early pioneer plant cover is rapidly establishing itself and includes mosses, the horsetail (Equisetum sp.), fireweed
(Epilobium latifolium), circular mats of mountain avens (Dryas drum- mondi), willow (Salix sp.), and alder (Alnus sp.) seedlings. Infre quently, moss can be seen growing on top of the rocks that constitute the ablation blanket of small dead ice masses.
Outwash is filling the heads of the inlets rapidly, andnumerous deltas are the typical modern outwash features. Outwash gravel and sand, in addition to till, can still be seen throughout much of Glacier
Bay Monument, but are best developed and preserved, a t le a s t in the northeastern part of the Monument, within the Muir Inlet area. Fluvial erosion is now developing an intricate deep-gullied pattern on the till and gravel d ep o sits, and w ill continue as long as remnant ice provides abundant meltwater or there is a lack of a dense vegetative cover.
The streams in the National Monument are small with the exception of the Dundas River east of the Brady Glacier. 5
The general grain of the topography is northwestward. Recent
faults control ice and stream drainage. The region is tectonically
unstable, with frequent minor earthquakes and occasional major shocks.
Wildlife is abundant and varied, including mammals such as
moose, coyote, porcupine, wolf, wolverine, various species of bear, and
many species of sea and land birds. The region abounds in fish. The
alpine animals include marmot and goat. For details concerning insects,
birds, mammals, and fish, the reader is referred to The Institute of
Polar Studies Report Number 20.
Climate
The climate of the Glacier Bay National Monument area is a
maritime-west-coast type varying regionally from a warm-temperate-rainy
clim ate with cool short summers, Koppen's clim atic type Cfc, as at
Juneau, to a rainy climate with cold winters and cool summers having prevailing winter rain but a wet summer also (Loewe, 1966). The latter
is Koppen's classification Dfs'c, with the coldest month below -3° C.
Upper Muir Inlet may tend toward the Dfs'c classification; only year- round meteorological data will tell. Small daily and annual tempera
ture ranges, high relative humidity, high fog frequency, considerable
cloudiness, and abundant precipitation are characteristic of the Glacier
Bay region. Temperature (Fig. 2) and precipitation (Fig. 3) are con trolled largely by topography and proximity to the Pacific Ocean.
At Nunatak Cove (Fig, 1), Muir Inlet, meteorological observations were recorded from June 23, 1963, to August 29, 1963, and from June 19, » i l n h U N I 18 / I ! i 1 • I n N /)h I I Ip 1 ! 16 i\ é •— I I \/’ I , l I . \ m I m 1 I IS 13 1 Vvy « to ■ < 'i* \ i è 0=
A
• \ A K/\ <»-4 e / \ A \ #-# V. V J / > v v . 0 ©“€T @...... " # A %». * • — « » 1 X < Ï /V V A# * * ------1963 V ...... 1964 V«.
20 25 10 15 20 25 30 10 15 20 25 30 5 to JUI€ JULY AUGUST SEPTEMBER 1 ‘
Figure 2. Maximum and minimum temperatures at Nunatak Cove for the 1963 and 1964 seasons.
O' «; 39 — 1963
1964 30.
i a. |1 ? f £ K) A" h I \ I I I I \ I - 9 I I \A 1 0 V I. . . ,l\ I..S /; —0-0-0- e~0~0 0 0-0-0 « 0
^ M I I I J J I I I J ^ I I I 1 M I 1 I M I I I M I I n I 1 I I J I I I I M 1 I I I I I I 1 I M I I 1 M I 1 I I J I I I M J M l I 25 10 15 20 25 30 10 15 20 25 30 JUNE 1 JULY AUGUST
Figure 3. Rainfall at Nunatak Cove for the 1963 and 1964 seasons. 8
1964, to September 12, 1964. These observations consisted of maximum and minimum temperatures, measurements of rainfall, and estimates of the percentage of overcast.
Wind
Summer winds in Muir Inlet are usually light and prevail from the southeast, with infrequent gales. During the summer of 1960, while working in Wachusett Inlet, a tributary of Muir Inlet on the west, the author experienced gale-force winds on a few occasions. Rapid down- slope or "glacier winds" are frequent in Upper Muir Inlet, producing a rev ersal of wind d ire c tio n from the normal p rev ailin g southeasterly flow to that of a northerly flow. These northerly winds become pro g ressiv ely more dominant and higher in v e lo c ity during the la te a f t e r noon and early evening hours. No wind v e lo c itie s were recorded in
Upper Muir Inlet during the summer seasons of 1963-1964, but rough estimates from observations of vegetation, flags, and movement of tent
"fly s" would suggest th a t wind speeds seldom reached a v elo city of more than 30 km/hour.
Temperature
In Muir Inlet, summers are cool and winters are mild compared to stations farther in the interior. The maximum summer temperature, recorded at Nunatak Cove camp during the seasons of 1963-1964, was
22® C. As yet, no data have been compiled for winter temperatures at this station although in 1965, Nunatak Cove was selected as the site for a year-round m eteorological sta tio n and data should soon be available for all seasons. From data which were recorded by the author, a table was compiled by Loewe (1966, p 23) to co n trast the mean monthly maximum and minimum temperatures of July and August of 1963 and 1964 at Nunatak
Cove with those at the Juneau weather station some 130 km to the southeast (Table 1).
TABLE 1
MEAN MONTHLY MAXIMUM AND MINIMUM TEMPERATURES (°C) AT NUNATAK COVE AND JUNEAU FOR JULY AND AUGUST, 1963-1964
Ju ly August Mean Mean Mean Mean Maximum Minimum Mean Maximum Minimum Mean
Nunatak Cove 15.0 5 10 15.0 5 10 Juneau 16,5 9 12.7 18 8.5 12.9
Table 2 contrasts the summer temperatures (June to September,
1963-1964) at Nunatak Cove with those at Bartlett Cove and shows the cooler conditions in Upper Muir Inlet. Appendix B provides comparative temperatures at Gustavus from the period 1951-1960. Occasionally winter tem peratures in Upper Muir In le t must drop below -18® C, because tem peratures below this have been recorded at the Bartlett Cove Ranger
Station. The first freezing observed during the 1964 field season at
Nunatak Cove, Upper Muir Inlet, occurred on September 8. At this time, frost covered the ground to sea level, and pancake ice was seen forming across the upper reaches of Muir Inlet. TABLE 2
MONTHLY MAXIMUM, MINIMUM, AND MEAN TEMPERATURES (®C) AT NUNATAK COVE AND BARTLETT COVE, 1963-1964 SEASONS
June July _ August September Max Min Mean Max Min Mean Max Min Mean Max Min Mean
Nunatak Cove 20® 4 10 21 3 10 22 2 10 No Data (Muir Inlet) 1963 Bartlett Cove 23 4 12 20 6 13 23 5 12 16 4 11 (Glacier Bay) 1963 Nunatak Cove 17^ 2 9 22 4 10 20 1 9 17^ 0 9 (Muir Inlet) 1964 Bartlett Cove 20^ 6 12 23® 6 12 19* 5 12 17 3 9 (Glacier Bay) 1964
Based on the period June 23, 1963 to June 30, 1963. ^Based on the period June 19, 1964 to June 30, 1964. 'Based on the period September 1, 1964 to September 12, 1964. ^Six days of the record missing at Bartlett Cove. 'Five days of the record missing at Bartlett Cove. Four days of the record missing at Bartlett Cove. 11
Cloudiness
Cloudiness in Upper Muir Inlet is prevalent, and days with only partial overcast are rare. This is probably true for most parts of
Glacier Bay National Monument. It is common to have at least 20 days of each summer month with 8/lOths to lO/lOths overcast. There are ex ceptions, as in August of 1963, when cloudless to only partly cloudy weather was experienced for eight consecutive days. Price (1962) reported similar periods of clear weather during the summer season of
1962. Loewe (1966, p 23) has compiled a table showing the distribution of clear, partly cloudy, and cloudy days from the author's weather data and from neighboring weather stations at Haines and Juneau.
Precipitation
The amount of p re c ip ita tio n at Nunatak Cove in Upper Muir In le t
(Fig, 3) is similar to that at Juneau (Loewe, 1966, p 24), which is approximately 130 km to the southeast. Extrapolation of the 1963-1964 weather data indicates that at Nunatak Cove there were 20 days with rain during the month of June, 19 during July, and only 13 during August.
Precipitation is abundant throughout Glacier Bay. Table 3 com pares the amount of rainfall at Nunatak Cove with that at Bartlett Cove for the months of June, July, August, and September of 1963-1964.
Loewe (1966) has estimated that precipitation probably is in the order of 1250 mm/year throughout G lacier Bay Monument. October is an excep tionally wet month. Loewe (1966) reported that rain falls three out of four days during this month. As might be expected, coastal stations 12
have excessive precipitation; the greatest recorded amounts were at
Little Port Walter at the south end of Chichagof Island. Here the
TABLE 3
TOTAL MONTHLY RAINFALL AT BARTLETT COVE AND NUNATAK COVE, 1963-1964 SEASONS
June, mm July, mm August, mm September, mm
Nunatak Cove, 32 75 60 No Data 1963
B a r tle tt Cove, 103 100 23 333 1963
Nunatak Cove, 32* 208 153 ob 1964
B a r tle tt Cove, 95 93 137 125 1964
*For period June 19, 1964 to June 30, 1964. ^For period September 1, 1964 to September 12, 1964, average annual precipitation is 5525 mm (221 inches). By closest known comparison, Cape Spencer, located at the extreme southwestern corner of
G lacier Bay Monument, receives about one-half th is amount per year.
Loewe (1966, p 21) has concisely summarized seasonal precipitation at five stations in southeastern Alaska, which all show a fall maximum.
He further stresses the fact that on mountain slopes above the inlets of Glacier Bay Monument, and especially in the high Fairweather Range, at least 10 meters of snow accumulate by late spring. This is a criti cal factor for the nourishment of glaciers in this area. Dr. Kermit
Bengston (1962) has reported that at an elevation of 1070 meters on the 13
Brady Glacier, in the western part of Glacier Bay Monument, a total of
970 cm of snow was recorded during the winter season of 1960-1961.
Even in the Muir Inlet area, heavy, wet, late spring snows are not uncommon (H. F. Jacot, 1960). According to W, 0. Field (1964), the snowline of August, 1964, on the peaks surrounding Muir Inlet was lower than usual. M. M, Miller (1967) reported that very important increases in snow accumulation at the 915 to 1373 meter level have been occurring in the Boundary Range near Juneau since the late 1950's. If this trend also holds for Muir Inlet and environs, then there should be a lowering of the n4v4 line compared to that of the 1940's.
After careful analysis of summer meteorological observations by several field parties since I960, Loewe states that "the summer obser vations at different points around Muir Inlet show no notable differ ences among each other except the obvious lower midday temperatures at the Casement Glacier station. Any physiographic or biological dif ferences among the sites are likely to be due to factors other than those of the summer climate".
An excellent summary on regional climate along the North Pacific
Coast can be seen in Heusser (i960, pp 27-34), Further data can be seen in Cooper (1942) and Goldthwait (1966a). PREVIOUS INVESTIGATIONS
The earliest recorded observations in the Glacier Bay area were probably made by Russian explorations along the southeastern Alaskan coast. The first known map and observations that outline the position of glacier termini in Glacier Bay National Monument were made by
La Perouse's party in Lituya Bay in 1786. This map was of great impor tance because it showed the Lituya and North Grillon Glaciers some
4 to 5 km behind their present positions (Klotz, 1899)(Goldthwait, et al., 1963). In July of 1794, Whidbey of Vancouver's expedition visited
Taylor Bay and Glacier Bay. At the time of this visit, Ice was blocking the mouth of Glacier Bay and may have been close to the position of the present National Park Service facility at Bartlett Cove(Fig. 1).
John Muir (1893, 1895, 1902, 1915) made several earlyvis its to the Muir Inlet area. His very first visit was with Indian guides in the fall of 1879 when he explored, sketched, and studied the glaciers funneling into what Is now Muir Inlet. He paid other visits to the same area in 1880. In 1890, he assisted Harry Fielding Reid with his work. He visited the area in 1896. His return in 1899 was under the auspices of the Harriman Alaskan Expedition. I t is no wonder th at this inlet and the glacier at its head bear the name ofJohn Muir, who was probably one of America's greatest naturalists.
During the late 1880's, the Muir Glacier terminus extended as far south as Mount Wright.
14 15
In 1886, G. F. Wright (1887) established, by means of the f ir s t truly detailed survey, the position of the Muir Ice Front south of
Adams Inlet, and also made a study of the motion of Muir Glacier, His results showed that the surface velocity of this glacier was 18,3 to
21,6 meters per day, and that the ice front was then some 27 km in advance of its 1964 position.
One of the most comprehensive e ffo rts of mapping the Muir
Glacier system was begun in 1890 by Professor H. F. Reid of Johns
Hopkins University. He completed his work in 1892 (Reid, 1892 and 1896),
The terminus was then just south of Adams Inlet (Figs. 4 and 5), and the area investigated by the present author, in 1963 and 1964, was overlain by about 600 meters of ice at the time of Reid's study, Reid also re ported during his investigation that Muir Inlet was entirely filled with gravel when the glaciers were farther back than they are today. This gravel-filling hypothesis was substantiated earlier by I, C, Russell
(1892) and again highlighted in R. P. Goldthwait's studies in 1959.
In 1895, the Canadian Boundary Survey mapped the entire drainage basin of Muir G lacier.
0. J. Klotz visited the Glacier Bay region in 1889 and photo graphs taken at that time show the Muir Glacier front as far south as the mouth of the Morse River (Fig. 6) and stretching across Muir Inlet to the northern flanks of Mount Wright. He noted from earlier charts and records that, between 1794 and 1894, ice in Glacier Bay retreated
72 km. This recession was at the rate of 0.8 km/year. During this same time span, the Brady Glacier advanced 8 km. Evidence for the latter is substantiated by the fact that a deserted Indian village 16
V . & Û Ê à L W C Â L t u n v f v •lltTCCNTH ANNVAL WEfOmT PW T I PC* «C
m %: y L tG E N O . MA«T« eioairrc AA*KC»vt 9c»U l GEOLOGIC MAP OF THE GLACIER 8AY REGION. Figure 4, Geologic map and ice position map of the Muir Glacier Basin in 1890. Compiled by H. P. Cushing as p art of H, F, Reid's study. Figure 5. Map of Glacier Bay and Muir Inlet (1890-1892) by H. F. Reid, et a l ., showing elevations of the surface of Muir G lacier and trib u ta rie s by contours. U.S. Geological Survey 16th Annual Report, 17 R) o f u i S c i S L o M i u o u « H « r 0t o . M A P O F GLACIER BAY ALAS KA Surveyed in 1890 and 92. INLET • BY Harry Fielding Reid. 1 n [ 19 *000 if' s ITTH-ÙMA'EE PK. «420Q & tM & ÊÊ(êê. s-'MÜIft /'. '•°*' 'V C^bemnant /a .* / . \ — 6L, > \ , < V SHOO ^ / \ ■ REO .y \ ' : , y " STUMP COV 'V"* I lit I \ N COVE -wto- J •7 - CULT'S O o a a t y «V f I \ ------‘'^1 COVE \ J » / * , HUSETT 2oa DKWMLIMIZCO »9000> V,, h u n t e h COVE 0UTWA3H 2700 î -i )'’ ? ) f t I il) «4000 streams /' y rw i MX. PEAK s • = QUILL I Jg) I GLACIERS I C I PHOTO STATIONS r~ â~ | GEODETIC SURVEY STATIONS d e lta s SI ALLUVIAL FANS \ ~ j - \ Mj^Hi^NtCAL ANALYSIS SAMPLE ♦MT9I»9 W m OHT GARrORTH 1 MILES aroline pt. ! f ?____ '____ f ^ 1 ?MIL0METERS ■■ END MO**" FIGURE 6 . MUm INLET SERREE IS. GLACIER BAY NATIONAL MONUMENT, ALASKA 20 reported south of the Brady Glacier by Vancouver in 1794 was buried under 305 meters of ice by 1894. This implies that during this span of time snow must have been accumulating at higher elevations as the freezing line moved up slope, while at lower elevations most of the precipitation was falling as rain. If this was the case, then ice from the lower northeastern névé basins would not have been able to sustain an ice front in equilibrium in Glacier Bay. W. 0, Field (1947, p 371) reported that the Muir G lacier r e ceded about 2750 meters from 1880 to 1899; yet between 1890 and 1892 there was an advance in the order of 915 meters. This was caused in part by local heavy snowfall and also by restriction of the width of Muir Inlet south of Adams Inlet. It was probably this advance that built a moraine which now extends as an arcuate bar eastward from Caroline Point to Garforth Island (Fig. 6), at the immediate western base of Mount Wright. Between 1899 and 1913, recession of Muir G lacier amounted to 12,8 km. In 1899, Adams In le t ice separated from Muir Inlet ice, drastically reducing the earlier mutual reinforcement. W. S. Cooper (1937, p 48) reported th at during two periods be tween observations, 1916-1921, and again from 1926-1929, no appreciable net change took place in the Muir Glacier terminus. W. 0. Field (1947, p 391) explains the ra te s of recession in Muir In le t as having been influenced by two factors, namely; the extent of the terminal ice ex posed to tidewater as determined by the depth of the inlet, and the length of the tidal ice cliff, and secondly by the degree of lateral constriction of the ice stream at the terminus caused by the basal topography or by the pressure of a tributary glacier. 21 R. S. Tarr and L. Martin made a brief study of Muir Glacier in 1911. Since that time, the record is much more detailed, highlighted by visits in 1916 by W, S. Cooper, 1919 by J. B. Mertie, Jr., and 1926 by B. S. Wood and W. 0. Field. The results of these and later studies by R, P. Goldthwait (1966b) dealing with positions of the Muir Glacier are shown by decades on Figure 7, W. O. Field states (1967) that between August of 1964 and September of 1966 the Muir Glacier terminus retreated 1700 meters (5576 feet). This is at the rate of about 567 meters per year (1858 feet). From observations of air photographs taken by Austin Post, it would appear that within the next three to five years the terminus of the Muir Glacier should no longer be tidal. Figure 8 shows the posi tio n of Muir G lacier in August, 1961, and in August, 1966. Figure 9 shows the re la tio n sh ip of Muir, Riggs, and McBride G laciers In August, 1961. W. S. Cooper (1921, 1923, 1924, 1931, 1937) foresaw many of the stratigraphie subtleties that have since been investigated and refined in Muir Inlet. His work, hampered by a much wider ice cover, showed amazing insight and his field studies were ahead of their time. Many of today's findings substantiate his earlier predictions. For example, the climax forest which he stated was buried by ice is still appearing from the re tre a tin g ice fro n ts, and h is studies of plant successions have served as a "springboard" for later, more-detailed studies. Valuable contributions that deal' with ice retreat, vegetation succession, soils, and stratigraphie problems include the reports of Cooper, as cited above. Field (1947), Lawrence (1958), Goldthwait (1963), Figure 7, Map of Muir Inlet region showing retreat of glacier fronts by decades since 1880. (a fte r Goldthwait) 22 23 %"'"t940 % SEULE ISLAM t mujMCTtflS GARFORTH 24 Figure 8. Oblique a e ria l photograph of Upper Muir In le t and Muir Glacier, looking northwest at Muir Névé Field and St. Elias Moun tains. Photograph taken in August, 1961, by Austin Post, Dashed line shows 1966 terminal position of Muir Glacier. MR = Muir Remnant Gla cier. Cliffs in foreground are White Thunder Ridge. Cloud-capped peaks west of Muir Remnant are part of Minnesota Ridge. 25 Figure 9. Air photograph looking north up Muir Inlet to the Takhinsha Mountains. Taken in August, 1961, by Austin Post. Muir Glacier at head of Inlet on the left, and Riggs Glacier, with a nunatak, on the right. White Thunder Ridge on lower left, McBride Valley Glacier on lower r ig h t, and McConnell Ridge between Riggs and McBride Valley Glaciers. Current terminal position of Riggs and McBride Glaciers is still the same as that seen on this photograph. Black Mountain is the peak on the upper right, above the cloud and the sharp bend in Riggs G lacier. 26 and Goldthwait, et al. (1966). R. P. Goldthwait (1963), in particular, has helped to clarify the complex glacial history of Muir Inlet by giving a firm base to the glacial chronology through radiocarbon dating of organic materials, especially trees in the position of growth. The most recent and thorough study of ice structures within stagnating ice has been made by Taylor (1962). The work of R. J. Price (1964) on the morphology and development of eskers and drainage changes in front of the Casement Glacier is a most valuable contribution and adds further to the stratigraphie history in Muir and Adams Inlets. GEOLOGIC SETTING General D. L. Rossman (1963a) has reported that rocks on the west side of Glacier Bay, east of the Fairweather Range, are predominantly sedi mentary, consisting chiefly of thin-bedded and massive limestones and some argillaceous rocks. He recognized five formations having a total exposed thickness of about 7930 meters and ranging in age from Late S ilu rian to Middle Devonian. The most abundant igneous rock he r e ported was diorite, ranging widely in composition and possibly includ ing rocks of more than one age and mode of origin. Other igneous rocks reported include quartz diorite, granodiorite, granite, gabbro, and mafic and silicic dike rocks. Figure 10 is a generalized geologic map of the Muir In le t area. Sedimentary Rocks The sedimentary section in Glacier Bay National Monument in cludes the Willoughby Limestone at the base, believed to be Late Silurian in age; the Tidal Formation, a widespread unit of argilla ceous rocks; the Pyramid Peak Limestone, also believed to be Late Silurian: the Rendu Formation, a unit composed of thin argillaceous beds and limestone whose age is uncertain; and the Black Cap Limestone which may range in age from Late Silurian to Middle Devonian. The Black Cap Limestone is especially fossiliferous. 27 Figure 10. Generalized Geologic Map of Upper Muir Inlet. Explanation: ■ Fault Late Wisconsin and Recent Surficial Deposits Jurassic-Cretaceous Igneous Rocks (d i o r i t e , g ra n o d io rite , and g ran ite) Paleozoic? Volcanic Rocks Devonian Black Cap Limestone ( fossiliferous) Paleozoic Metasedimentary Rocks ( a r g illite s ) 28 29 7 ^ MMATM ONE BOOSC a t «àCHUSETT NLET KLOTZ MILES 30 In Upper Muir In le t, the basal rock u n it is composed prim arily of variegated highly indurated thin-bedded to thinly laminated argil laceous metasedimentary rocks of Paleozoic age, minor shale, limestone, and limy graywacke. Marble occurs near the intrusions. These basal rocks are folded, faulted, and intruded by dikes of probable Cretaceous age and are possibly a northward extension of the Rendu Formation,, which is known to unconformably underlie the Black Cap Limestone. The Black Cap Limestone appears to overlie Rendu-type sediments on the east side of Upper Muir Inlet. Much detailed work remains to be done in this area in order to make a justifiable correlation with the rocks to the south in Tidal Inlet and around the periphery of Glacier Bay. Metasedimentary rocks reported to be several hundred feet thick (Rossman, 1963a, p 25) crop out at Goose Cove immediately south of "The Nunatak", These rocks resemble those exposed on "The Nunatak" and are horizontally bedded, variegated, and intruded by numerous lig h t- colored dikes. Rossman has indicated that they are tuffs with minor beds of limestone. Since they appear to ce less indurated and deformed than similar rocks of theRendu Formation, they have been mapped as a separate undifferentiated and possibly younger sedimentary unit. W. S. Twenhofel and others (1946) have subdivided the basal meta sedimentary rocks on "The Nunatak", where they have been intruded by a small stock of quartz monzonite with which molybdenite and other sul phides are associated. The oldest rock unit here is dark blue fine grained thin-bedded limestone with a few shaly beds. Overlying this basal unit is a thick section of hornfels, ranging from green to pink to brown, which is divided into three units. All are fine-grained, 31 hard, dense, and closely resemble chert, but the lower hornfels unit is thin-bedded and contains a few limy beds, the middle hornfels unit is characteristically thin-bedded, and the upper hornfels unit is thick bedded, Devonian age has been suggested for this basal unit. Many light- and dark-colored dikes cut these Paleozoic metasediments and the dikes have been reported by Twenhofel (1946, p 13) to range in composi tion from hornblende andésite porphyry to dacite porphyry. In some outcrops the thin-bedded argillite shows well-developed rhythmic bedding. Above the basal argillaceous rocks on the west side of Upper Muir Inlet lies the Black Cap Limestone, a thick unit of light- to dark-grey fossiliferous marine limestone. This formation is thin- bedded at the base and becomes progressively thicker-bedded upward. Numerous fo ssils were observed by the author in the lower thin-bedded part of this formation. Corals, possible bryozoans, trilobite fragments, gastropods, pelecypods, and brachiopods were recognized. Specimens of this material were submitted to Dr. C. W. Merriam of the Paleontologi cal and Stratigraphie Branch of the U.S. Geological Survey at Menlo Park, California. Dr. Merriam (1967) has, to date, identified the following fossils: the solitary rugose coral Peripaedium, tabulate corals belonging to the genus Thamnopora, and a brachlopod which could either be Athyris or Eomartiniopsis. These genera, identified by Merriam, confirm Devonian age for the Black Cap Limestone. The upper part of the Black Cap Limestone is pale gray and is cut by numerous calcite veinlets. The thickness of this formation was not measured. 32 The rocks within the formation are mildly folded, strike northwesterly, and dip gently to steeply southwest. Intrusive Rocks Plutons of diorite and quartz diorite with granite and grano- dioritic phases crop out on both sides of Upper Muir Inlet in prominent rounded knobs, horned peaks, and high jagged ridges. The highest peaks north of Muir Inlet along the crest of the Takhinsha Range are composed of plutonic d io r itic to g ra n o d io ritic rocks (D. A. Brew, 1967). Rocks of this type have intruded and metamorphosed the Paleozoic rocks of Upper Muir Inlet. Idaho Ridge, south and west of Wachusett Inlet, con stitutes one of three batholithic masses in this part of the National Monument. The Idaho Ridge Batholith can be traced the entire length of Wachusett In le t, or from Queen In le t to Muir In le t (Figs. 1 and 6). Similar foliated granitic rocks crop out northward across Wachusett Inlet, the Bruce Hills, and Minnesota Ridge, and terminate against hornfels of White Thunder Ridge (Figs. 1 and 8) south of the present terminus of Muir Glacier. Another long, narrow, east-trending batholith extends from the northern tip of White Thunder Ridge, where Muir Inlet makes a 90-degree bend, across the inlet onto McConnell Ridge north of the McBride G lacier (Figs. 1 and 6 ), and thence eastward across the central part of the Casement Glacier to the National Monument boundary in the Chilkat Mountains. It is probably this body of diorite that provides the source for cobbles in the outwash and till near the mouth of Coleman Creek and in the la te ra l moraines of McBride G lacier. D. A. Brew (1967) reports a mass of granitic rocks of batholithic 33 proportions, along the crest of the Takhinsha Mountains, that extends in an east-w est d ire c tio n from the head of the névé basin of Riggs Glacier to that of the Casement Glacier, Brew reports from reconnais sance in this area that rocks in this pluton are mostly "foliated sphene-bearing biotite-hornblende tonalité (quartz diorite) and are in contact, on the south, with a spectacular zone of foliated migmatite consisting of various amphibolite masses in biotite-hornblende tona lité". These rocks have been transported from the north some 20 km into Upper Muir Inlet. Other known stocks (plutons) of granitic rocks, foliated and nonfoliated, crop out on the north and west sides of the Klotz Hills over an area of approximately 10 sq km. Rocks of sim ilar lith o lo g y crop out on the west side of Muir Inlet from the high point, Knob "G", (Fig. 6) and the Coast and Geodetic Survey Station "Morse", northward to Hunter Cove, and as isolated patches to Wachusett Point at the mouth of Wachusett Inlet. These outcrops are certainly part of the Idaho Ridge Batholith. In the Curtis Hills (Fig. 6), on the north side of the mouth of Wachusett Inlet, similar rock types cover an area of some 8 sq km. This is probably part of the Idaho Ridge Batholithic complex. With the exception of the southeastern part, almost the entire length of Minnesota Ridge appears to be composed of d io rite lik e th a t seen by the author In reconnaissance along the crest of Idaho Ridge. At the extreme southern end of White Thunder Ridge, a very small exposure of diorite is in contact with metasedimentary rocks. On the east side of Muir Inlet granitic rocks crop out along the narrow north-south ridge of Red Mountain that separates the McBride 34 Remnant Valley from the Casement Valley (Fig. 10). These g ra n itic rocks extend as far south as Forest Creek, where they are in contact with volcanic rocks. The main summit of Red Mountain is not composed of granitic rocks but of sediments and metasediments. North of Red Mountain, granitic rocks are again encountered on the slopes of Coleman Peak. Coleman Peak is also composed of granitic rocks. Several very small plutons of diorite intrude the Black Cap Limestone north of Forest Creek. These do not appear on Figure 10. The central part of "The Nunatak" i s composed of quartz monzo- • nite. D, A. Brew (1967) has also reported a large body of quartz monzonite near the head of Casement G lacier, The occurrence of th is rock is certainly not unique to "The Nunatak". The eastern one-third of Van Horn Ridge is composed of rocks very similar to those found near Coleman Peak, mainly diorite to quartz diorite or granodiorite. D. L. Rossman (1963a, p 33) reported a very small circular body of gabbro approximately 3.2 km due east of Goose Cove (Fig. 1). This intrusive occurs within the Black Cap Limestone and, according to Rossman, probably represents a volcanic plug. Although i t was not seen by the author, its identification as a plug is supported by the fact that volcanic breccia is found about 2 km south, at Hill 728 (Fig. 6) just north of Forest Creek gorge. Age of Plutonic Granitic Rocks J. C. Reed and R. R. Coats (1941) believed that these plutonic rocks were intruded in Late Jurassic or Early Cretaceous time. 35 M. A. Lanphere, et al. (1964) have reported a 93-million-year age (lead- alpha age of zircon) for a hornblende-biotite granodiorite sampled at Turner Lake, east of Juneau. If the plutons west of the Coast Range Batholith are truly satellites of that batholith, then by inference they may be the same age, since Lanphere, et al. (1964) have reported that the Coast Range Batholith of the mainland intrudes rocks as young as Early Cretaceous. D. L. Rossman (1963a, p 29) reports that diorite. Intrudes rocks of Mesozoic age on Chichagof Island, immediately south of Glacier Bay Monument (Fig. l) , and is therefore younger than these rocks. Again, Lanphere, et al. (1964) have demonstrated that some granitic rocks south of Glacier Bay Monument are of early Paleozoic age, probably as old as Ordovician. The history of igneous intrusives in the southeastern Alaskan Archipelago is not as simple as it was once believed to be. Dike Rocks Dike rocks are very abundant throughout Muir Inlet. They range in composition from mafic to silicic and are found in the greatest numbers intruding sedimentary and metasedimentary rocks, though some intrude igneous rocks. What appear to be dark diabasic to basaltic dikes cut granitic rocks near the head of Wachusett and Muir Inlets. The term lamprophyric might be more descriptive of many of them. Pheno- crysts of hornblende and biotite are quite common in a fine-grained matrix. Unusually fine exposures can be seen on the recently degla ciated eastern side of White Thunder Ridge and along the south flank of Mount Brock near the head of Muir Inlet (Figs. 1 ,6 , and 8). The age 36 relationships of the dikes are not known to this author. They range in thickness from just a few centimeters to several meters. Pegmatite dikes are uncommon in this area. It would seem that all of these dikes are younger than the granitic rock intrusions, as in many places one can see inclusions of g ra n itic rocks in the fine-grained dark dikes. D. L. Rossman (1963a, p 3 5 ) has suggested that the light-colored dikes may be of Cretaceous age. Some may be as young as T e rtiary . Early detailed studies on "The Nunatak" by W. S. Twenhofel, et al. (1964) suggested that here the basaltic dikes and sills are earliest in the intrusive dike sequence, and that they were followed by intrusion of quartz monzonite. The quartz monzonite was then intruded by numerous smaller dikes ranging in composition from andésite porphyry to dacite porphyry. At many, but not a l l , outcrops i t was noted th at the lig h t- colored dikes weather more rapidly than the host rock and cause indenta tions in the exposures along the coast. Frost shattering (Fig. 11) attacks many of these dikes more rapidly than the plutonic rocks and produces long scree slopes at their base. Volcanic Rocks D, A. Brew (1967) reports wide exposures of volcanic rock in the greater Muir Inlet area (Fig. lO). He has mapped three types of volcanics: namely, amygdaloidal flows like those seen in the Adams Inlet region, dark-weathering volcanic breccia like the outcrop at 37 Figure 11, Frost-shattered dike rock on the south side of "The Nunatak". Trenching shovel for scale. 38 Forest Creek, and reddish-weathering fault-bounded volcanic breccia like the rocks reported by Basel ton (1966) north of Red Mountain. According to Brew, perhaps the largest exposures of volcanic rocks in this part of Glacier Bay Monument occur in the Immediate vicinity of Adams Inlet both to the south and to the west. Details of this rock type will be described in future publications by both D. A, Brew and G. D, McKenzie. Of concern to the author are the volcanic rocks east and north of Muir Inlet. Brew has mapped three long, narrow east-trending volcanic outcrops th a t extend en echelon from the McBride G lacier eastward be neath the Casement Glacier and terminate against granitic, carbonate, and hornfelsic rocks near the Chilkat Range divide (Fig. l). Some of the common landmarks north of the McBride Remnant Valley which appear as black outcrops on mountain sides are now known to be exposures of volcanic rock. This is true for Black Mountain, 10 km north of Van Horn Ridge, and Sitth-gha-ee Peak (Fig. 6), 5 km north of Van Horn Ridge. Brew reports that Black Mountain is composed mostly of dense metavolcanics and dark phylllte with marble layers and that the highest parts of the peak contain very dark-green amygdaloidal meta basalt. Pieces of this amygdaloidal metabasalt were seen in ground moraine and medial moraines in the McBride Remnant Valley. From Brew's work, it is now known that limestone conglomerate probably comes from both Black Mountain and from Sitth-gha-ee Peak. In pebble counts on the McBride Remnant ice block, p h y lllte or schistose pebbles are in places common constituents. Indeed these could also be part of the metavol- canic complex that lies just north of the Muir Inlet area. 39 The first ridge immediately north of Red Mountain is composed of reddish-weathering volcanic breccia. This breccia was traced as far east as the ice-dammed lake on the west side of Casement Glacier. This ridge is referred to as Middle Mountain and can be seen on Figure 6. The rock here has not been identified by pétrographie means, but in hand specimen it is an intermediate porphyritic volcanic rock of various shades of red. What appear to be alblte-twinned euhedral plagioclase phenocrysts make up about 50 percent of the rock, quartz phenocrysts make up 5 percent of the rock, and the rest is fine-grained matrix. It is possible that this rock is related to the volcanic rock at Forest Creek and also to rocks in the volcanic complex to the north. Middle Mountain apparently is bounded by faults both on its north and south sides. These faults are followed by two streams which drain snowfields on Red Mountain, Middle Mountain, and the Coleman Peak area. Pebble counts on Red Mountain alluvial fan first indicated the presence of volcanic rocks in this region and the high percentage of breccia fragments on the fans along the eastern boundary of the McBride Rem nant Valley reflect the local source area. Metasedimentary Rocks Metasedimentary rocks crop out within the Upper Muir Inlet area. According to D. A. Brew (1967), these rocks were originally limy gray- wackes and shales that were subsequently hornfelsed around granitic intrusions. To the north of Muir Inlet, the section, according to Brew, consists of graywacke, limy siltstone and shale, and gray phylllte. North of Wachusett Inlet, outcrops of hornfelsed rocks are common. 40 They crop out at the rock drumlin near the entrance to Goose Cove (Hill 416, Fig. 6), throughout a wide area north and west of the Curtis Hills, and on the high peaks along the southeastern part of Minnesota Ridge. From Minnesota Ridge, they continue north and east as outcrops in the Westdahl Hills, throughout the peaks of White Thunder Ridge, and across the head of Muir Inlet to Mount Brock. West ajnd east of Mount Brock these rocks crop out over an area of at least 260 sq km. Like the batholithic intrusive rocks north of Muir Inlet, these sediments and metasediments trend east-west as long, somewhat narrow en-echelon outcrops. In the immediate area of the McBride Remnant, metasediments are seen on "The Nunatak", along the crest and flanks of Van Horn Ridge, as a long, narrow sliver of outcrop on the west flank of Red Mountain, on Sealers Island in the Middle of Muir Inlet, just west of Goose Cove, and along the east and west flanks of the lower p art of the Casement Glacier, as well as at the terminus of the Casement Glacier. The abundance of these metasediments on both sides of Upper Muir Inlet accounts for their dominance in almost any pebble count made throughout this area. Since pebbles of this lithology are highly siliceous, they are particularly resistant to weathering. Carbonate Rocks In addition to the limy units that occur in the metasedimentary and sedimentary units discussed above, there are three other types of carbonates north of Casement G lacier and Muir In le t, These have been seen in reconnaissance by D. A. Brew (1967). He reports that small 41 patches of what appear to be reef limestones occur within the volcanics and phylllte on both sides of McBride Glacier north of McConnell Ridge, The second type of carbonate is a medium- to thick-bedded fossiliferous light-gray limestone that strikes east-west, occurs north of the Case ment Glacier, and extends westward as far as the high névé of the Riggs Glacier. This type of limestone contains both brachiopods and corals. Although, at present, there is no detailed information about this rock type, it may possibly be a facies of the Black Cap Limestone, which crops out just to the east of "The Nunatak". A third type of limestone that Brew has seen in reconnaissance is a thin- to very thin-bedded graphitic limestone just south of the divide of the Takhinsha Mountains. Limestone of th is type was not recognized in the McBride Remnant region. It would be easily confused with several of the other types of lime stones. The wide outcrop of fossiliferous Black Cap Limestone that makes up the group of low, rounded crag-and-tail hills at the eastern side of the McBride Remnant Valley (Fig. 6) has already been described. Its relationship to a small limestone outcrop on the west side of Sitth- gha-ee Peak is not known. Small scattered patches of carbonate rocks have been reported by Brew (1967) within the metasediments of White Thunder Ridge. He also has mapped several outcrops of carbonate rocks around the summit and flanks of Mount Brock. What these relationships are is not known, but will be reported in the near future by Brew and oth ers. 42 Ore Minerals Disseminated sulfide minerals occur in all rock types seen in Upper Muir Inlet, especially in the sedimentary and metasedimentary rocks, and associated with quartzose phases of granitic intrusives. Pyrite occurs most commonly as scatted blebs and veinlets. Bornite, ch alco p y rite, m alachite, and other copper sulphides were frequently seen in flo a t from the limy hornfelsed sediments surrounding McBride Remnant Valley. Deposits of molybdenite are associated with quartz monzonite within "The Nunatak" and have been the subject of much dis cussion and in v estig atio n since th is knob f i r s t appeared through the ice in 1911. At one time or another, more than a dozen different prospectors have staked claims over "The Nunatak" and in the summer of 1964 an intensive geophysical search was made to try to determine the extent of "Nunatak-type" rocks. Undoubtedly, molybdenite is associated with other quartz monzonite intrusions in the upper drainage basins of the Muir-Casement G lacier system. Grab samples taken from "The Nunatak" by Rossman (1963a) showed tra c e s of copper, s ilv e r, and gold. A more comprehensive discussion of past mineral prospects and their potential is given by D. L. Rossman (1963a, pp 48-52). Because ore enrichment is known to follow faults, it might be worthwhile for future prospectors to concentrate their attention on a series of east-west transverse faults between Forest Creek on the south and Coleman Peak on the north. C ertainly the limy deposits close to igneous plutons could be hosts for contact metasomatic deposits. 43 Brief Geologic History Throughout at least the middle of the Paleozoic Era, the Glacier. Bay National Monument region was the site of marine deposition as wit nessed by the thick and extensive deposits of fossiliferous marine limestones. It is believed that by early Mesozoic time uplift occurred in this area and two parallel geosynclines developed; one along the west coast and one extending parallel to what is now referred to as the "Inside Passage". These troughs recieved very thick deposits of sedimentary and volcanic rocks during the Mesozoic Era. Deep burial of Mesozoic sediments may have led to the development of "magmatization”, mountain making, and associated intrusions toward the end of Mesozoic time. These widespread intrusions are the Coast Range Batholith and its associated satellite plutons (batholiths). Faults developed after consolidation of these batholiths and, according to D. L. Rossman (1963a), these faults were later the locus for smaller quartz-diorite intrusive bodies. Still later in the Mesozoic, intrusions of gabbro occurred like those cropping out within the Fairweather Range (Rossman, 1963b). The last vestiges of igneous activity are recorded by the eruption of Mount Edgecumbe on Kruzof Island, east of Sitka, believed to have taken place in early Postglacial time. GLACIAL STRATIGRAPHY General The Late Pleistocene and recent stratigraphy in the Muir Inlet area can be divided into seven units. Division into seven units is possible when one takes into consideration the fact that recent out- wash reported by R, P. Goldthwait (1966b) should be included in the stratigraphie sequence. The stratigraphie units in ascending order include: the Forest Creek Formation, the Muir Formation, the lower, middle, and upper members of the Van Horn Formation, the Glacier Bay Formation, and the Seal River Formation (recent outwash). Figure 12 is a composite diagrammatic stratigraphie section for this area showing ages and dates as determined by radiocarbon analyses. Figures 13 to 15 are general correlation diagrams of the sections measured around Muir Inlet. Many more sections were measured than are shown in the diagrams, but to include them would have caused undue crowding. Figure 16 illu s tr a te s some of the detailed stratigraphie relationships of these units and Figure 17 is a map of Upper Muir In le t showing the location of the stratigraphie sections illustrated in Figures 13 to 15. 44 ^^•\'^Eskers, Karnes, Crevasse Fillings] RECENT 2120 ± 115(11610) & 2735 ± 160(1122) BAY FM“ a X J 1400 ± 90(1162) & LATE NEOGLACIAL Q,;,^ark Gray 1^1440 ± 120(11302) (LITTLE ICE AGE) From 1710 è 60(Y306) :'(UPPER)^.0 SEAL RIVER FM to 2175 è 100(188) RECENT VAN HORN Q INSET OUTWASH a FM . EARLY 1660 ± 110(11304) NEOGLACIAL Lacustrine & 1765 ± 50(Y304) Laminated Gray Outwash MIDDLE Slits O • o -O'O From 1975 ± 60(185) to 2340 ± 115(11612) o O » GLACIAL (LOWER) From 3650 ± 100(1126)} 2620 ± 120(11305) VAN HORN FM to 4750 ± 160(1124) } C>. From 3290 ± 55 (Y303) HYPSITHERMAL S>. . .Ô ^to 4775 ± 250(180) 6650 dt 100(1163) Dates on Stumps . . <3 5235 ± 200(182) Buried by Outwash MUIR FM Û ^ ^ à LATE WISCONSIN Û Sandy Loam Til 6335 ± 220(181) reddish-yellow 10,400 ± 260(11615) 7025 ± 270(191)8. Dates on Logs Buried 7075 ± 250(184) by Drift FOREST CREEK FM_ From 10,400 ± 260(11615)' Clay, S ilt, Sand — & Shells to 13,960 ± 360(GX0460) ______MUIR INLET LATE WISCONSIN — ------_ SEA Figure 12, Diagrammatic stratigraphie section in Upper Muir Inlet with ages and dates. Carbon 14 dates are in years before the present. Stumps and logs in solid black, (after Goldthwait, 1966)(Modified by Haselton) A Figure 13. Correlation diagrams of stratigraphie sections Nos. 1 through 9. See Figure 17 for location. 46 STRATIGRAPHY ON EAST SIDE MUIR INLET NORTH 366 m. 1 4 0 - Ul \ /\ oc 2 , / NUNATAK KNOB BEDROCK \ I 4 0 - m â m 1 4 0 - IZO- w 100- s 4 0 - 2 0 - I6 0 i- 1 4 0 - SOUTH 400 800 1200 1600 2000 120 100- o METERS 8 0 - VERTICAL EXAGGERATION lOX r 60 — 4 0 - 2 0 - -t» ? — •-J 48 NORTH STRATIGRAPHY ON WEST SIDE MUIR INLET SOUTH MUIR REMNANT RIVER NORTH MUIR REMNANT RIVER WEST EAST 100 - UPPER WEST * 4 0 - 83 = 2 0 - MINNESOTA RIOOE 300m -V SOUTH CURTIS HILLS # 230 m. NORTHEAST ' ' T " I MINNESOTA RIDGE WACHUSETT INLET WEST 120 WESTDAHL HILLS i S i s l i è WESTDAHL MLLS 100 STUM P COVE « 8 0 NORTH WESTDAHL HILLS a. :Gi l e0 400 m 800 1200 1600 m 2000 '/N/A = 4 0 - 1 I I I I I I I I V n ;, v 20- METERS VERTICAL EXAGGERATION OX vO Figure 15. Correlation diagrams of stratigraphie sections Nos, 19 through 24. See Figure 17 for location. 50 STRATIGRAPHY ON WEST SIDE MUIR INLET NORTH WACHUSETT INLET l O O h WEST ROWLEE POINT OENSON 60“ SOUTH 4 0 - \ ROWLEE POINT 2 0 - \ (£CO SI20|- SOUTH 100- 80-DENSON SOUTH MORSE RIVER BULL NORTH MORSE RIVER 4 Ü - 20- COVERED INTERVAL MUIR TILL GLACIER BAY TILL LATE NEDGLACIAL WISCONSIN^ 0 400 800 1200 1600 2000 FOREST CREEK VAN HORN - UPPER Y < - K 1 I I I I I I METERS JURASSIC BEDROCK HTPSITHERMAL< VAN HORN - MIDDLE VERTICAL EXAGGERATION K)X CRETACEOUS! VAN HORN - LOWER m (ji CANYON CHEEK ICE-RAFTED PEBBLE WITH DISTURBED BEDDING DEFORMED LAKE SEDIMENTS aa a a a RELATIVELY DNWEATHERED TILL 120 — ■120 RELATIVELY UNWEATHERED GRAVEL LAKE BEDS I MOSTLY SILT B FINE SAND I RELATIVELY WEATHERED GRAVEL RELATIVELY WEATHERED TILL CROSS BEDDED SAND NORTH CREEK BO 80 ORANGE CREEK V ERTICA L EXAGGERATION 10% O A 0 Ol TILL CREEK 0.0 e\ ' 0 UPPER 3 d.o\oO'o'ro hehber î ^ . ° 0.0■ o o FORMATION '■ o 40 — 4 0 a a a ■Û Û Û A Ù NUIR TILL 6 6 6 a ' X a. a a ,a a a .a a a a a * * ^ a a .a a a a a a a a . a a a^a^a* ' ^ a 4 a ^ _ ^------COVERED INTERVAL NORTH SOUTH —iQ METERS 400 800 1200 1600 2000 2400 Figure 16. Detailed stratigraphie relationships between Canyon Creek and North Creek on the east CJl side of Muir Inlet. See Figure 17 for location. ro THIRD CREEK NORTH CM. TNO-TIIL CR. KLOTZ HILLS COVE NORTH FORK NUIR REHRANT RIVER ROWLEE POINT WESTDAHL DENSON ^ POINT h u n t e r L c o v e o •18 CURTIS HILLS MILES BULL J KILOMETERS WHFORK HUR RENHANT RIVER STATION 7 Figure 17. Map of Upper Muir Inlet showing locations of the stratigraphie sections illustrated in Figures 13 through 16. Ü1 CO 54 Late Wisconsin Strata Basal T ill Perhaps the oldest unit in the stratigraphie succession in the Muir Inlet area is a till. Such a relationship has been reported by G. D. McKenzie (1967) where a t i l l was seen lying d ire c tly on bedrock and beneath the Forest Creek Formation, This relationship was not seen in Upper Muir Inlet and is not included in the seven stratigraphie units, but is mentioned for the sake of the completeness of the strati graphie record. Forest Creek Formation The Forest Creek Formation, ranging in thickness from 0 to 7 meters, is blue-gray to gray thin-bedded fossiliferous marine clay and silt that appears massive in fresh exposures. Pebbles in the clay and silt suggest that ice may have been nearby when these fine elastics were deposited. The type section of the Forest Creek Formation occurs at a small rock gorge (Fig. 18) about 2 km up Forest Creek from Muir Inlet. It rests on a striated porphyritic dike-rock and volcanic com plex. On top of the clay and silt are irregular lenses or pods of clean white fine- to medium-grained thin-bedded sand, which probably represents a former beach deposit. In places, the sand has been stained to a brilliant limonite-orange, and the clay below this has a blocky structure. The exposure of the Forest Creek Formation at the gorge is covered in part by recent talus (Fig. 18) and by what probably is older 55 Figure 18. Forest Creek Gorge, type locality for the Forest Creek Formation, Man in foreground is standing on the fossiliferous marine clay. 56 solifluction material composed of angular boulders and cobbles from the neighboring slopes to the east. Pebble counts made in the talus- solifluction material confirm the local nature and source in ledges just above. On the south side of Forest Creek gorge the stratigraphie section consists of the following units in ascending order; (1) Resting on bedrock is 1.6 meters of blue fossiliferous marine clay with occasional pebbles. (2) Medium- to fine-grained white thin-bedded sand, in lenses where eroded, but may occur as a bright orange-red where coated by iron-oxide stain. (3) 1.5 meters of gray angular to subangular highly oxidized slope material that resemble gravel on first appearance, but may be all a result of solifluction. The basal part is unweathered and is bound by a matrix of coarse highly lithified slope scree (solifluction) resembling, at first glance, weathered till. The upper part of this solifluc tion material has a rusty-reddish soil. This is an inter- stadial soil. (4) 2,9 meters of laminated lacustrine silts and clays that show deformation and contain some pebbles. (5) 1.3 meters of cross-bedded sand and gravel that make up a stream terrace. On the north side of this same gorge, and measured from stream level up-section, the following units may be seen: ( 1) 6.9 meters of blue pebble-bearing fossiliferous marine 57 clay with many barnacle plates still in the holdfast position. (2) 0.8 meters of gray medium-grained fossiliferous sand, possibly a littoral sand or well-sorted beach sand. (3) 2 meters of bluish-gray sand with some clay, containing abundant subrounded pebbles. These pebbles suggest the possibility of berg-rafting at the time of deposition by bergs from retreating ice. This is probably the same lacustrine sediment that is on the south side of the gorge, but here i t is partly masked by thick slump. (4) 1.1 meters of angular boulders in a coarse sand and pebbly matrix. This is the same slope-creep, slump, and so liflu c tion layer that is exposed on the south side of the gorge. Many of the angular pebbles and boulders are highly oxidized or completely weathered. Near the top of the unit is the same reddish-orange soil that was reported above. (5) 10 cm of lacustrine silt, highly bleached and containing some organic material. (6) 5 cm of less oxidized, fine, angular slope material (soli fluction?) whose interstices are filled by mud. (?) 30 cm of laminated lake silts oxidized to an olive gray. (8) Capped by stream terrace gravels of the Seal River Forma tion. The deposit at the base of the type section is at approximately 25 meters above sea level. 58 Another exposure of the Forest Creek Formation was examined near the headwaters of Forest Creek, Here the formation overlies dioritic rock at an elevation of about 60 meters above sea level. At this location it is only a few centimeters to a meter in thickness where exposed in outcrop or penetrated by trenching. The formation is directly overlain by an oxidized till, the Muir Formation. The f i r s t radiocarbon date from sh ells from the Forest Creek Formation gave an age of 10,000 ± 220 years B.P. (Sample 1-1303). G. D. McKenzie, in 1966, submitted a log for radiocarbon dating from the marine material of the type section. This wood is 11,170 ± 225 years old (Sample 1-2396), An additional sample of shells recently 14 submitted for carbon analysis by the author gave an age of 13,960 ± 360 years B.P. (Sample GXO-460). Furthermore, McKenzie (1967) reports that he has found an exposure of the Forest Creek Formation on the north side of Adams Inlet at almost the exact elevation of the type section, R, P. Goldthwait (1966b) reports another exposure south of Casement G lacier and east of Seal River. Peat dated from McKenzie's exposure is 10,940 ± 155 years old (Sample 1-2395). The most recent datings are all surprisingly close, especially the wood and peat sample dates. McKenzie's observation that till rests on bedrock, and is directly below the Forest Creek Formation in his study area, raises doubt as to whether one can still call the Forest Creek Formation the o ld est u n it in the stra tig ra p h ie column in Upper Muir I n le t. Of even greater surprise, and of equal significance, is the fact that A. T. Ovenshine (1967), while on reconnaissance for the U.S. Geological Survey, found the Forest Creek Formation cropping out on bedrock near the 59 terminus of the Reid Glacier in the northwestern part of Glacier Bay Monument, some 40 km from the type section. Dating of shells from this exposure may substantiate a correlation with Muir and Adams Inlets, and as Ovenshine has reported, "will permit two conclusions (1) that Late Wisconsin marine conditions prevailed throughout Glacier Bay and (2) that during the last 10,000 years there has not been large-scale differential uplift between Muir Inlet and the northwest arm of Glacier Bay". If this is borne out in the dating, Ovenshine believes it might lend some support to his idea that the Fairweather Range did not undergo differential uplift causing a glacial advance that could have reached the mouth of Muir In le t about 4000 years ago. The Forest Creek Formation contains abundant marine fossils, particularly pelecypods, gastropods, and barnacles. Identification of many of these fossils has been made by Dr. Aurele LaRocque of the Department of Geology at The Ohio State University. Gastropods include Colus spitzberqensis, Trichotropis borealis, and Neptunea lyrata. The pelecypods identified are Trachycardium quadragenarium, Mya arenaria« Macoma sp. , and Hiatella arctica. The large pecten Chlamys islandicus is rath er common, as are numerous barnacle p la te s, many of which are in their holdfast positions on pebbles. Peat at the interface between the Forest Creek Formation and an overlying oxidized and indurated till, at Locality 7B on Figure 17, is 10,400 é 260 years B.P. (Sample 1-1615). This date suggests that the overlying till at this location is Late Wisconsin. 60 Muir Formation The Muir Formation, the lower of two tills in the section, is named for its several exposures along the east side of Muir Inlet. This till is a sandy loam in which cobbles and boulders make up a minor percentage of the coarse constituents. It was seen lying on bedrock at only one exposure, where seen in other exposures the base was not observed. R. P. Goldthwait (1963, 1966b) has reported the Muir Formation lying on bedrock in Wachusett Inlet. It is overlain by either fine sand and lacustrine silt or coarse gravel of the Van Horn Formation. In Adams Inlet, G. D, McKenzie (1967) found what may be this till underlying the Forest Creek Formation. The color of the Muir Formation contrasts strongly with the dark-gray to drab-brown unoxi dized younger Glacier Bay Formation (Till). The Muir Formation is yellowish-brown to orange, or reddish-brown in its oxidized upper por tio n s. The depth of oxidation ranges from 1 to 5 m eters. Below the oxidized zone, at Orange Creek (Fig. 6), it was bluish-gray with yellow mottling. In most exposures, it is well indurated and has not been leached. Near the headwaters of Forest Creek, immediately north of Section 7B (Fig. 17), the till has a well-developed soil at the top with abundant wood and/or forest mat materials. Radiocarbon dating shows that trees, in their position of original growth, in the overlying Lower Van Horn Gravel are on the order of 7000 years old, and since peat which directly overlies the Muir Formation in Adams Inlet is 10,940 ± 155 years old (Sample 1-2395), this gives a minimum age for the basal till. These ages indicate that the time span between 61 Wisconsin Ice retreat and inlet filling was adequate for the develop ment of a mature so il and a climax fo rest. The Muir Formation lies directly on bedrock in a deep stream gully at the north end of "The Nunatak", approximately 1.6 km north of Nunatak Cove (Fig. 19). Here it is overlain by lacustrine sediments of the middle member of the Van Horn Formation. It is overlain by the middle member of the Van Horn Formation at Two-Till Creek (Fig. 20), about 0.3 km north of "The Nunatak". Its most northerly exposure was seen at Orange Creek, 0.6 km north of "The Nunatak",where it is directly overlain by the lower member of the Van Horn Formation; the base of the Muir Formation was not seen here. However, since bedrock lies close by, it is assumed that the Muir Formation rests on bedrock. All of the above-mentioned localities are on the east side of Upper Muir Inlet. Most exposures of this till are in deep gullies where streams have dissected the overlying till and thick gravels. Pebble counts were made in the Muir Till at each of the five localities where the till is exposed (Table 4 and Appendix I). These pebble counts show the following average lithology: 22 percent diorite or related granitic rocks, 29 percent igneous dike rocks, 27 percent metamorphic rocks, and 22 percent calcareous rocks. Table 4 compares the pebble lithology of the Muir Formation with those for the Glacier Bay Formation, ab latio n t i l l , the gravel members of the Van Horn Formation, and the Seal River Formation. These are averages of the total pebble counts from each formation’. Figure 21 compares the mechanical analyses of fractions less than 2 mm for these same units. 6 2 Figure 19. Looking south at "The Nunatak", with peaks on the south side of Adams Inlet in the background. Note deep gullying and stripping of till and gravel from around the flanks of "The Nunatak", North Creek is the deep gully in shadow on the north side. 63 Figure 20. Stratigraphy at Two-Till Creek. (A) Late Wisconsin Muir Formation (Till); (B) lacustrine clay, silt, and cross-bedded sand of middle member of the Van Horn Formation; (C) Glacier Bay Formation (Neoglacial Till). TABLE 4 AVERAGE PEBBLE LITOOLOGIES OF THE MUIR FORMATION, GLACIER BAY FORMATION, ABLATION TILL, VAN HORN FORMATION, AND MODERN OUTWASH Muir Modern Fm, Glacier Lower Gravel Upper Gravel Outwash, Average Average Till Bay Fm. Ablation Member of Van Member of Van Seal River of all of all Rock Type 6" T ill,32 Till, 10 Horn Fm., 13 Horn Fm., 28 Fm., 4 Tills Gravels Igneous Dike Rock 24 29 31 27 28 32 28 29 Limestone 19 25 20 21 23 20 22 22 Metasediments, 23 21 15 24 19 15 20 18 Hornfels Amphibolite 0 1 0.3 0.5 2 0 0.5 0.8 Plutonic Igneous, 34 24 30 27 28 33 29 30 mostly diorite Schist 0 0 1.6 0 0 0 0.6 0.2 Gneiss 0 0 0 0 0 0.2 0 0 Greenstone 0 0 1.3 0 0 0.5 0.5 0.2 Indicates number of pebble counts. Figure 21. Mechanical composition of tills and gravel. See Figure 6 for location of samples. 65 100% Clay Lower Van Horn Gravel Clay X Sandy A s ilt y C lay / I Glacier Bay Till / \ciay (Little Ice Age) ^Sandy \ Clay ^ l l t y \ lay Loanrt loam ^ la v Loaii\ JO A Muir T ill oam (Late Wisconsin) Sandy S ilty Loam Loam Sand Silt ,60 a3-io a 5 ^ 3 -'3 ' — lY V O' 100% Sand 10 20 30 40 50 60 70 80 90 100% S ilt OS 67 A typical mechanical analysis for the Muir Formation shows 61 percent sand, 32 percent silt, and 7 percent clay (0.002-0.0002 mm). Five fabric analyses were made on the Muir Formation, one for each exposure. The fabric at Orange Creek demonstrates that basal ice moved directly down Muir Inlet during Late Wisconsin time. The fabric maximum at Two-Till Creek was N 50° W, whereas at North Creek it was east-west. The east-west fabric at North Creek, at the north end of "The Nunatak", may reflect splitting or divergence of the ice around this high rock knob; however, this strong divergence in direction may indicate flow till that moved down over a steep bedrock gradient. West of the Casement Glacier, 0.4 km from the present terminus, another east-w est fabric d ire c tio n was recorded and a t th is lo c a lity i t would seem that bedrock topography was responsible for the east-west flow since a 50-meter bedrock hill would have turned basal ice at this loca tion. Pebbles in the till have a gentle northerly dip in the direction from which the ice advanced. In general, the fabric of the Muir Forma tion has a more westerly maximum than that for the Glacier Bay Formation. Van Horn Formation The Van Horn Formation, named for exposures on the east side of Muir Inlet, south of Van Horn Ridge, (Figs. 1 and 6) consists of three members. These include a lower and an upper bouldery to cobbly gravel unit, and lacustrine deposits that normally occur between the gravel units, but which may occur within the gravels. The Van Horn Formation ranges in thickness from 3 to 90 meters in the area studied (Figs. 22 and 23), and may be thicker in some of the exposures in the adjoining 68 Figure 22. Part of Canyon Creek b lu ffs north of "The Nunatak" exposing the lower member of the Van Horn Formation (A), the lacustrine silts and cross-bedded sands of the middle member (B), the horizontally bedded gravels of the upper member (C), and the Glacier Bay Formation (Till) at (D). 69 Figure 23, South side of Canyon C r e e k illustrating the crude bedding and sorting of the bouldery upper member of the Van Horn Forma tion (C), and the overlying Glacier Bay Formation (bouldery-clayey till) (D). The light-colored boulders are diorite (d). 70 inlets. It overlies the Muir Formation and is, in turn, overlain by the younger, unweathered bouldery Glacier Bay Formation. Although the relationships of the lower contact are obscured in many areas, the Van Horn Formation overlies bedrock in some exposures. Radiocarbon dates of 7025 ± 270 years B.P, (Sample 1-58-20, Goldthwait, 1963) and 1765 j: 50 years B.P. (Sample 1-304, Goldthwait, 1963) were obtained from tre e s in th e ir o rig in al position of growth in the lower and the upper parts, respectively, of the Van Horn Formation (Table 5). This 5000-year interval has been referred to as Hypsithermal time by investi gators in Alaska, and by Goldthwait in his earlier work (1963, p 37). Pebble counts (Table 4 and Appendix I) suggest th at the sources for the Van Horn gravels were local. Dips in most of the gravel expo sures where cross-bedding did not obscure the relationships too much were low, generally in the order of a few degrees. This is what would be expected for typical glacial outwash-spreads like those of the Van Horn Formation, Local deltaic conditions are reflected by consistently steep foreset-type bedding in sands and gravels like those on the west side of Muir Inlet near the Coast and Geodetic Station "Denson". Here sands and gravels dip as much as 20 degrees to the east. With the ex ception of dips on foreset bedding and steep cross-bedding, most dip directions are toward the axis of Muir Inlet or are parallel to sub parallel to its longitudinal direction, A marked exception is on the west side of the inlet south of the Morse River, where the regional dip of the gravels and lacustrine sediments' is to the north. TABLE 5 RADIOCARBON DATES FROM SHELLS AND WOOD IN THE FOREST CREEK FORMATION, VAN HORN FORMATION, AND GLACIER BAY FORMATION Meters Above Above Unit Name & Base of Sea 14 Sample No. C Date Unit Level Location Collector Forest Creek Formation GX0460 13,960 ± 360 B.P. - - 25 Forest Creek Gorge, Haselton* shells in matrix 1-2396 11,170 ± 225 B.P. ? 30? Forest Creek Gorge, McKenzie wood 1-1615 10,400 ± 260 B.P. Top of 60 Upper Forest Creek, Haselton formation wood 1-1303 10,000 ± 220 B.P. 5 27 Forest Creek Gorge, Haselton shells 1-2395 10,940 ± 155 at Base? 30? Adams In le t, wood McKenzie Van Horn Formation Lower Member 7075 ± 250 B.P. 9 North side of Stump Goldthwait 1-84 Cove, prone log Lower Member 7025 ± 270 B.P. 6 Nunatak Cove, south Goldthwait 1-91 side, prone log Lower Member 6650 ± 100 B.P. 1 Wachusett Inlet, north Burns 1-163 shore, tree in place TABLE 5, (Continued) Meters Above Above Unit Name & Base of Sea Sample No. Date Unit Level Location Collector Van Horn Formation Lower Member 6335 è 200 B.P. 26 Nunatak Cove, south Goldthwait 1-81 side, prone log Lower Member 5235 ± 200 B.P. 17 Nunatak Cove, south Goldthwait 1-82 side, prone log Upper Member 2190 ± 105 600 Casement G lacier, west Goldthwait 1-2302 side, 2 km from snout, tree in place Upper Member 2175 è 100 B.P, 60 Forest Creek, tree in Goldthwait 1-88 place Upper Member 1710 ± 60 B.P. 55 Hunter Cove, tree in Lawrence Y-306 place Upper Member 1660 ± 110 B.P. 120 North Creek, north Haselton 1-1304 side of The Nunatak, prone log Glacier Bay Formation, T ill 1-122 2735 ± 160 B.P. 220 Curtiss Hills, north Goldthwait side of Sta, 7, tree in t i l l -vi to TABLE 5, (Continued) Meters Above Above Unit Name & - Base of Sea Sample No. C Date Unit Level Location Collector Glacier Bay Formation, T ill 1-1610 2120 ± 115 B.P. ca450 White Thunder Ridge, Field and west side, tree in Janda t i l l 1-2300 1690 ± 100 B.P. 125 Adams Inlet, south Goldthwait side, prone log in t i l l 1-2301 1560 ± 95 55 Adams Inlet, south Goldthwait side, log in till Goldthwait, Haselton, and McKenzie--Ohio State University; Lawrence--U niversity of Minnesota; FieId--American Geographical Society; Burns—Ohio Wesleyan University; Janda— U.S. National'Park Service, 74 Hypsithermal-- Lower Member of the Van Horn Formation The lower, gravel member of the Van Horn Formation ranges in thickness from 0 to 57 meters. It is more highly weathered and more indurated than the upper gravel member. It has been oxidized to a characteristic yellow to reddish color. This lower member is not present in all exposures. It overlies the Muir Formation immediately south of Canyon Creek, but overlies bedrock on the north side of the Westdahl H ills. I t is exposed best between Van Horn Ridge and Goose Cove on the east side of Muir Inlet. One of the thickest exposures is in Canyon Creek (Figs. 13 and 22), midway between Van Horn Ridge and "The Nunatak" (Figs. 4 and 6). An unusual change in lith o lo g y of the lower member occurs in exposures at and near Section 23 (Fig. 15) where the gravel has a most distinct reddish-brown color and is com posed of brown-weathering limy boulders. It is believed, but as yet not demonstrated, that the source of the lower gravels here may have been the Tidal Inlet area. Groundwater percolation is an important factor in the weathering of the gravels. Weathering increases adjacent to organic layers in the gravel units where organic acids have been concentrated. Just below these organic layers, pebble weathering counts show a 5- to 10-percent increase in pebbles that are totally weathered. Most of the lithologies in th i s member, as well as in the upper member, have dissem inated s u l fide minerals, which have undoubtedly aided in chemical weathering through the production of weak solutions of iron sulphate and sulfuric 75 acid. Coupled with this is the discoloration in the lower Van Horn member due to hem atite and lim onite sta in in g , produced in p a rt by the weathering of biotite and hornblende in the diorite pebbles, cobbles, and boulders. Certainly the lower yellow and red gravel is older than the fresh gray gravel of the upper member. Deposition of the lower . gravel unit was intermittent because two distinct forest horizons can be seen along the gravel bluffs south of Nunatak Cove, These old forest horizons are separated by several meters. W. S. Cooper (1937, p 43) reported 15 to 30 meters of separation between forest horizons in what are now id e n tifie d as Van Horn g rav els. Figure 24 shows the separation of forest horizons in the upper Van Horn gravel. The gravels of the lower member of the Van Horn Formation appear poorly bedded and sorted. Some beds or lenses of coarse cross-bedded sand occur in most exposures. Reversals in dip directions, as outlined by cross-bedding, reflect cut-and-fill structures developed during deposition in braided streams. Generally, the bedding of the gravel is about horizontal. Marked changes in the size of the clasts in the gravel undoubtedly reflect seasonal changes in the volume of runoff which would, in turn, have affected load, and also the position of the braided channels would have shifted through time. In some cases there may have been minor fluctuations in the positions of the glacier termini, however, this is not reflected in the stratigraphy. Sands and silts are particularly well developed beneath forest beds which are traceable through the lower gravel from Nunatak Cove to Goose Cove. Soil development appears to have just started beneath the forest horizons, but was halted by burial due to outwash. These soils 76 Figure 24. Two forest horizons in the upper gravel member of the Van Horn Formation at Upper Forest Creek. Limbs s t i l l attached to some trees (a) testifying to their burial in gravel. Upper forest horizon (b) is a mat of limbs and logs ca. 1500 years old, below the Glacier Bay Formation (Till); lower forest horizon (c). Upper Van Horn member (A), Glacier Bay Formation (B). Note bouldery alluvial fans (d). Man circled for scale. 77 are easy to recognize due to the bright colors of oxidation, and are associated with organic mats which contain twigs, branches, cones, and roots from the old forest floor. Early Neoglacial-- Middle Member of the Van Horn Formation The la c u strin e member of the Van Horn Formation is composed of silt, very fine sand, and clay. Where graded bedding occurs, the coarser fraction may be pebbly sand (Fig. 25). This member is exposed in many of the stream cuts along both shores of Muir Inlet. It is re ported by Goldthwait (1963) to have been seen in Wachusett Inlet, and McKenzie (1967) reports lacustrine deposits on the south side of Adams Inlet, A massive stratified clay that is partly marine was reported by Ovenshine (1967) near the mouth of the Beartrack River, south of Muir Inlet, It is possible that some of this material may be lacustrine. These lake sediments range from blue-gray to brown to yellow, depending on the amount o f sand and the degree of oxidation, and, where seen by the author, range in thickness from a few centimeters to 12 meters; individual laminae range in thickness from 1 to 5 cm. Very fine cross bedding, occasional ripple marks, and well-developed graded bedding, suggesting turbidity currents, occur in the coarsest sand layers; these features suggest that these exposures are near marginal parts of the lake and reflect shallow water. The first stages of lake filling seem to have been by fine to medium sand, followed by coarser material, which gives way upwards to the upper Van Horn gravel. Locally, branches, twigs, or small logs are buried in the lake sediments and 78 Figure 25. Exposure of the lacustrine member of the Van Horn Formation at Two-Till Creek, showing graded bedding. 79 here and there large "knots" of limbs, branches, and stems of trees are seen where they have been rafted into place. What appear to be the results of iceberg rafting are indicated by the occurrence of cobbles and pebbles in lake laminae, especially near the terminus of the McBride G lacier and at an exposure 1 km upstream from the mouth of the North Fork of the Muir Remnant River. Here pockets of till are present in the upper part of the lake sediments where they have been deformed by ice shove. At many places, folding and overturning have occurred in some laminae in the silts and clays, whereas the laminae above and below the zone of disturbance have not been deformed. Even where gradients are low, much of this spotty deformation within an undeformed sequence of lake laminae may have resulted from turbidity currents, differential compaction, or as H. W. Theakstone (1965) reports, by differential freezing and thawing. Laminae in pairs of light and dark layers occur in many expo sures. Although these laminae resemble varves, they will be referred to as rhythmites because the length of time represented by each pair is uncertain. Graded bedding is well displayed at Two-Till Creek, 0.8 km north of "The Nunatak" (Fig. 25). Figure 26 is an exposure of lacustrine clays and silts at Nunatak Cove, Six mechanical analyses were made on lake sediments and the results are shown in Figure 27. All except one of the lacustrine sam ples are silt loam. For comparison, a separate analysis was made on surface d e lta ic m aterial, which proved to be sandy loam. In most places, the lacustrine member of the Van Horn Formation lie s between the lower and upper gravel members (Fig. 22), but in an 80 Figure 26. Rhythmites In lacustrine clays and silts of the middle member of the Van Horn Formation overlying the lower Van Horn gravel member on the south side of Nunatak Cove. Figure 27, Mechanical composition of lacustrine silts. See Figure 6 for location of samples. 81 10036 Clay Clay 0 Lacustrine Deposits Sand// (Middle Van Horn) ci#y Sandy \ Clay ^ llty \ JO lay LoaaX Loam Æ lav Loaa^ L o a n S a n d y S i l t y L o a n Loam S a n d S i l t ,60 M3 M 6 * • M l •M2 • M4 00 10036 Sand 10036 S ilt NO 83 exposure on the north side of "The Nunatak", it rests directly on the Muir Till, and in an exposure about 2 km south of the Coast and Geo detic Survey Station "Bull", lacustrine sediments are found lying above what is thought to be the upper member of the Van Horn gravel. One of the most continuous exposures of lake sediments extends from Canyon Creek, north of "The Nunatak", to Goose Cove Creek (Fig. 6). North of Nunatak Cove, similar lacustrine deposits occur higher in the section near the top of the upper g rav el. At Canyon Creek, the lake sediments pinch out both to the east and to the west as well as in a north-south direction and are missing in the stratigraphie sequence from here to the McBride Glacier, where they occur again, but on top of Upper Van Horn gravel. These stratigraphie situations suggest the possibility of two episodes of lakes. Radiocarbon dates of pieces of wood from near the top and bottom of these lacustrine sediments at various localities in Muir Inlet are shown in Table 6 and Figure 12, Additional dates are given in recent publications by R. P, Goldthwait (1963 and 1966), Most of the wood that was used to date the lakes or lake was not in its original posi tion of growth, but was washed into place. The assumption is that the wood was buried in the outwash deposits soon after death, R. P. Goldthwait (1963 and 1966) has suggested th at one lak e, not two, or many small lakes, extended the entire length of Muir Inlet and also into the tributaries of Wachusett and Adams Inlets, If so, this lake was as much as 30 km long and 450 meters (1500 feet) deep, as the lacustrine sediments have been found to elevations of 270 meters (886 feet) above sea level on the south side of Adams Inlet, Soundings TABLE 6 RADIOCARBON DATES ON WOOD ABOVE AND BELOW LACUSTRINE DEPOSITS OF THE MIDDLE MEMBER OF THE VAN HORN FORMATION Wood Above Elev. Above Wood Below Elev. Above Lake Deposits, Sea Level, Lake Deposits, Sea Level, aqe meters aqe meters Location Collector 4775 è 250 B.P. 15 Goose Cove Goldthwait 1-80 2265 ± 80 B.P. ? 4330 ± 80 B.P. 15 Goose Cove Lawrence Y-301 Y-302 1765 ± 50 B.P. 41 3290 ±55 B.P. 11 Hunter Cove Lawrence Y-304 Y-303 10 m above lake sediment 4750 ± 160 B.P. 24 Camp Creek Goldthwait 1-124 3655 ± 100 B.P. 41 Camp Creek Goldthwait I-59-1D 3650 ± 100 B.P. 41 Camp Creek Goldthwait 1-126 3175 ± 220 B.P. 42 Geikie Inlet, Goldthwait 1-58-6 Glacier Bay 2340 ± 115 B.P. 54 4640 ± 160 B.P. 50 Canyon Creek Haselton 1-1612 1-1613 4560 ± 140 B.P. 34 Two-Till Creek Haselton 1-1616 00 TABLE 6 é (Continued) Wood Above Elev. Above Wood Below Elev. Above Lake Deposits, Sea Level, Lake Deposits, Sea Level, aqe meters aqe meters Location Collector 2620 ± 120 B.P. 31 Forest Creek Haselton , 1-1305 Gorge In lake silts Im below the top 1975 ± 150 B.P. 15 Adams Island, Goldthwait 1-85 Adams Inlet 1980 ± 100 B.P. 20 Adams In le t, McKenzie 1-2394 SW corner 00 86 in Muir Inlet by the Coast and Geodetic Survey have shown a depth of at least 182 meters (600 feet). Goldthwait believes that Muir Inlet was dammed by a major advance of ice down Glacier Bay during early Neo glacial time. This would have been the initial phase of the Neoglacial ice advance out of the high Fairweather Range in the northwestern part of G lacier Bay Monument, and may have commenced about 4000 to 4500 years ago. The similarity of radiocarbon dates at or near the top and bottom of the lacustrine deposits throughout the stratigraphie sections in Muir and Wachusett Inlets, do show a common time of beginning for lake development and suggest that these deposits represent part of one large lake. If this is true, then this lake could have had a very undulating bottom in order for the lake deposits to be so widely dis tributed stratlgraphically in the Van Horn Formation. An alternative would be to interpret the lacustrine deposits at different stratigraphie levels in the Van Horn Formation as indicating the presence of more than one lake. The valley-train deposit which extended down Muir Inlet during Hypsithermal time could have dammed side tributaries, causing streams to become impounded. From the strati graphie evidence in Upper Muir Inlet, it is difficult to demonstrate conclusively that a single lake once filled all of Muir Inlet and Its tributary arms. Logs, limbs, and twigs, as well as other organic materials, have been found both beneath, within, and on top of the lacustrine deposits. From 10 radiocarbon datings (Samples 1-80, -85,-123, -124, -126, -164, -1613, -1616, and Y-301, -303), it now appears that this lake phase 87 lasted about 2000 years. Wood below the lacustrine sediments dates 4500-4200 years B.P, and above the lacustrine sediments generally 2600-2200 years B.P. The presence of la c u strin e sediments on both sides of Upper Muir Inlet together with new dates above and below these sediments, which agree closely with previous dates by D. B, Lawrence (1958) and R. P. Goldthwait (1963), add further strength to the hypothesis that Muir Inlet was dammed by ice moving down Glacier Bay in early Neoglacial time. Investigations by A. I. Ovenshine (1967), in the fall of 1965, lead him to believe that a lake or lakes in Muir Inlet was created by outwash-damming at the mouth of Muir Inlet. He thinks that the dark reddish-brown lower gravels at station "Bull" are not equivalent to the lower Van Horn Formation, but are probably the equivalent of the middle Van Horn member. The author did note th a t south of the section in dispute, lacustrine sediments again appear above the upper gravel outwash. Uncertainty concerning the lake question should be cleared up in part when dates are obtained from below and above lacustrine deposits in both the valley of the Beartrack River and from Geikie Inlet, The ice that advanced down Glacier Bay to dam Muir Inlet must also have dammed Geikie Inlet at about the same time, and would have created a contemporary lake there. From current work in Adams In le t by McKenzie, i t would seem th at there is a late Neoglacial history of lakes in that area that developed subsequent to the lake or lakes in Muir Inlet, G. D. McKenzie (1967) 88 reports having found two lacustrine units within the thick outwash sands and gravels,separated by a Neoglacial till which dates younger than 1980 ± 100 years B.P, (Sample 1-2394, McKenzie, 1967). A, T. Ovenshine (1967) reports twig-bearing Hypsithermal gravels 240 meters above sea level near the mouth of Johns Hopkins Inlet and bark from gravel in Tarr Inlet. This wood in northwestern Glacier Bay still does not preclude the advance of ice suggested by R. P. Gold thwait (1966b) in early Neoglacial time. If anything, dating of the wood may help to "pin down" more precisely the time of the ice advance down Glacier Bay. Certainly in the 3000-4000 year time span of the Hypsithermal, a climax forest could easily have been established in this part of Glacier Bay. The ice could then have advanced into the forest carrying most of the wood out of the deep fjords which are so well developed in this part of the National Monument. W, S. Cooper (1937, p 42) outlined a similar hypothesis when he stated, "There is no definite evidence of ancient forest in Reid Arm (northwestern Glacier Bay), but it seems inconceivable that vegeta- tional development should not have extended along its shores. These are steep, smooth, and regular, and there are practically no bordering lowlands. All traces of vegetation might easily have been destroyed by the advancing ice. There is a possibility, too, that local climatic conditions in these narrow valleys may have been unfavorable to forest development". Other work by Cooper (1942) demonstrated an analogous case in Prince William Sound near the head of the Gulf of Alaska. 89 Middle Neoglacial-- Upper Member of the Van Horn Formation The upper gravel member, which ranges in thickness from 3 to 75 meters, overlies the lacustrine sediments at most sections. This upper unit is fairly well-bedded, poorly sorted, and whitish-gray (Fig. 28). Cross-bedded channel sand lenses as much as one meter in thickness occur throughout the unit. Locally, pebbles in the gravel exhibit imbricate structure (Fig. 29)> and cobble-to-boulder size material occurs within a few meters of the top of this member at Canyon Creek (Fig. 24). Immediately north of Section 7A and at Section 18, as seen on the location map of Figure 17, this upper unit contains unusually thick amounts of cross-bedded well-sorted sand (Fig. 30). The exposure on the north side of Minnesota Ridge (Section 18, Fig. 17) exhibits many beds of deformed sand with other beds above still undisturbed (Fig. 31). Because the sands here do not contain interbedded tills, it is suggested that they were deformed not by ice, but during and after deposition. The upper gravel member along the north flank of Minnesota Ridge is exceptionally thick, and shows many local erosional unconformities, especially well-developed cross-bedding that suggests the cutting and filling of braided channels, and an overall gentle dip of the entire deposit eastward toward Muir Inlet. The deformation of the sandy beds is probably due to settling and collapse of water-saturated sediments, as slump structures are evident in this area. In many ways, the deposits here resemble the upper sandy 90 Figure 28. Upper gravel member o f the Van Horn Formation forming high bluffs on the north side of Forest Creek, about 2 km west of the gorge. Note development of alluvial fans at the base of the waste-accumulation slope. Figure 29. Cross-bedded channel sands and gravels in the upper gravel member of the Van Horn Formation on the north side of Forest Creek, Same location as Figure 28, 91 Figure 30, Upper Van Horn gravel re stin g on bedrock (B) a t the mouth of Fault Creek. Here trees (t) occur In the growth position on bedrock and as prone logs (p). Cross-bedded sands are shown as dark spots in the gravel above the bedrock, (See Fig. 6 for location.) Figure 31, Collapse structure in a cross-bedded sandy unit of the Upper Van Horn gravel on the north side of Minnesota Ridge near the head of Stump Cove alluvial fan. 92 deposits on the northeastern side of Tree Mountain (Fig, l) in Adams Inlet, seen by the author in reconnaissance in I960. The increase in clast size, greater angularity of the clasts, and much cruder bedding toward the top of the member strongly suggest the close proximity of advancing Late Neoglacial ice (Figs 32 and 33). The results of 9 radiocarbon dates (Table 5) taken from wood at or just above the top of the middle member of the Van Horn Formation, or near or at the base of the upper member of the Van Horn Formation demonstrate the time span of proglacial outwash filling which preceded the oncoming of the Late Neoglacial ice advance. These dates indicate that this upper outwash was building into Muir Inlet from about 2340 ± 115 years B.P, (Sample 1-1612) to 1660 ± 110 years B.P. (Sample 1-1304), This upper member is directly overlain by the Glacier Bay Formation and, since there are no intermediate tills in the strati graphie sequence in this part of Muir Inlet, one must assume that any fluctuations of glacier termini from the Takhinsha Mountains during this time of filling never reached far enough down the inlets to be re fle c te d as individual t i l l layers within the Upper Van Horn grav el. The Upper Van Horn member is similar in lithology to the lower member. Pebble counts indicate th at the upper member is ric h e r in diorite than the lower member (Table 1), yet this is in part a result of weathering. Glacier Bay Formation The Glacier Bay Formation, or Late Neoglacial Till, blankets almost all older deposits and is found at elevations of at least 93 Figure 32. Crudely bedded, bouldery gravel of the upper member of the Van Horn Formation resting unconformably on collapsed cross- bedded sands on the north side of Minnesota Ridge. Stump Cove delta and Westdahl Hills in the background. Figure 33. Contact of Upper Van Horn gravel (A) and G lacier Bay Formation (Till) (B), north side of Forest Creek. 94 610 meters (2000 feet). This till was laid down during the last advance of the ice from the Takhinsha Mountains and the Boundary Ranges of British Columbia. Ice from this last Neoglacial invasion is still rapidly retreating near the head of Muir Inlet, The name Glacier Bay Formation is here proposed for the youngest till because it is a rock unit that is exposed not only in Muir Inlet, but also throughout the bays and in le ts of G lacier Bay National Monument, The Glacier Bay Formation rests directly on the Van Horn Forma tion, from which many of its rounded clasts are derived (Figs. 33 and 34), It has a darker gray color than the subjacent gravels, and con trasts rather markedly with the light gray to yellow and red colors of the Muir Formation, It is a bouldery-to cobbly-rich loam or sandy loam with a slightly lower sand content than the underlying Muir Formation. It is unweathered and unleached and shows little or no oxidation. Since i t is composed in p a rt of the reworked upper gravel member of the Van Horn Formation, the contact between the two is gradational in some areas (Fig. 33). It ranges in thickness from less than one meter to over 30 meters, and is exposed high up on the sides of ridges and bed rock knobs throughout the area. Streams, slope wash, and solifluction are rapidly removing it from unvegetated slopes (Figs. 35 and 36), Where the till is still unvegetated, gullies give a small-scale badland topography. I t i s on the G lacier Bay Formation th a t modern so ils are developing and across which pioneer plants are once more establishing themselves. This till and the underlying gravels have been streamlined into numerous elongate drumlin hills, which are being exposed rapidly by the modern-day ice retreat. 95 Figure 34, Unconformable relationship between the Upper Van Horn member and Glacier Bay Formation at Larsen Creek (see Fig, 6 for lo c a tio n ), 96 Figure 35. Looking west across McBride Remnant Valley from the lower slopes of Red Mountain, Stream erosion is dissecting the drum- lin iz e d t i l l and gravel h ills in the centerground. (l) McBride Remnant River, (2) McBride alluvial fan, (3) "The Nunatak", (4) Nunatak Cove, (5) Goose Cove, (6) Wachusett Inlet, (7) Limestone Hills. Note nova tion hollows in the foreground and "block streams" on Red Mountain. Figure 36. Looking west to Muir Inlet across northern part of McBride Remnant Valley. (l) Red Mountain Creek alluvial fan, (2) Middle Mountain, (3) Van Horn Ridge, (4) Middle Creek fan, (5) Coleman Creek fan, (6) McBride Remnant ice, (7) Canyon Creek, (8) ice-cored kame, (9) White Thunder Ridge. 97 Twenty-six mechanical analyses were made from the Glacier Bay Formation. A typical analysis of the sand-clay range is as follows: 54 percent sand, 36 percent silt, and 10 percent clay (in the range 0.002-0.0002 mm). The sand content of the Glacier Bay Formation is usually less than that of the older Muir Formation (Fig. 21 and location on Fig. 6). A number of pebble counts were made in th is upper t i l l . I t is interesting to note that there is no outstanding difference in the lithology when all pebble counts are averaged for the upper and lower gravels and the upper and lower tills (Table 4). When the lower (Muir) and upper (Glacier Bay) Formations are compared, a greater percentage of granitic rocks is seen in the Muir Formation. This probably re flects large areas of uncovered basement rock and an abundant talus accumulation which was available for the Late Wisconsin ice to pick up. On a rock knob near the south end of the Burroughs G lacier, Station 7 of W. 0, Field (1947, p 376)(Fig. 6), wood covered by the Glacier Bay Formation, and therefore overridden by the last ice advance, has been dated at 2735 ± 160 years B.P. (Sample 1-122) (Goldthwait, 1963), This last ice advance was probably under way several centuries before this. A new date for the onset of the late Neoglacial ice advance will be reported at a future time by A. T. Ovenshine. He reports (1967) having sampled a portion of a tree in the position of growth which was rooted in peat and found near the terminus of the Cushing Glacier northwest of the Bruce Hills. To the author's knowledge, this locality is the closest yet found to the upper drainage area of the Muir Glacier system, and dating of this wood should reflect 98 more closely the onset of Neoglacial ice advance into this part of G lacier Bay Monument. Wood from a stump in p lace, high up on the west side of White Thunder Ridge, has been dated at 2100 ± 115 years B.P. (Sample 1-1610). It was collected by W, 0. Field and C. V. Janda near Field's photographic Station 13 (Fig. 6). This date indicates thick ening of the ice to 500 meters above sea level 2000 years B.P. Presumably at this time, the ice covered all except the highest peaks in Upper Muir Inlet. If Muir Glacier ice was this thick near the crest of White Thunder Ridge 2100 years ago, certainly its terminus must have been well south of this position at sea level. Radiocarbon dating of wood (Haselton, 1966) at the base of the Glacier Bay Till near the present snout of the Casement Glacier indicates that Casement Glacier ice had reached within 2 km of Muir Inlet 1440 ± 120 years B.P, (Sample 1-1302). In Adams Inlet, G. D. McKenzie (1967) has found trees in place in lacus trine silts some 20 meters below a late Neoglacial till. Dating of wood from this horizon has indicated that these trees are 1980 ± 100 years B.P, (Sample 1-2394). Therefore, ice moved into southern Adams Inlet after this date and probably at about the same time as the Case ment G lacier was advancing from the north. Furthermore, McKenzie has suggested in discussions that glacial ice in Muir Inlet may have been responsible for damming Adams Inlet, creating the lake that started to form there about 2000 years ago. Although perhaps too sweeping an inference, lack of any other stratigraphie evidence in Upper Muir Inlet 99 suggests that Ice moving down Muir Inlet during the span of the above- mentioned dates (1440 to 1980 years.B.P.) was the same ice that reached the mouth of Glacier Bay in the early 1600's. Near the terminus of the Reid Glacier, A, T.Ovenshine (1967) reports having found a compact clayey till whose age he believes will demonstrate a post-Wisconsin, pre-Late Neoglacial advance. This third till has not been reported before in this part of the National Monument and it may coincide with McKenzie's intermediate till. Dating of a peat above this till near the Reid Glacier will give an upper limit to its age and wood in gravels above the till will further substantiate the age (Ovenshine, 1967), This may turn out to be the ice that moved south to dam Muir Inlet at the end of Hypsithermal time. Seal River Formation A detailed study of the region south of the terminus of the Casement Glacier was made by R, J. Price during the summer of 1962, He noted that throughout large parts of the Casement outwash plain, gravels were found to rest on the older Hypsithermal gravels or on top of the Glacier Bay Formation (Late Neoglacial Till), He called this latest deposit "Upper Gravels". He reported that they range from, "a few inches to 70 feet in thickness, and form mounds and ridges” . These upper gravels Price said, "were laid down by meltwaters associated with the most recent wastage of the Casement Glacier", R. P. Goldthwait has named the stream now draining the Casement Glacier the "Seal River", and the outwash deposits associated with it are referred to by him as the "Seal River Formation". These modern deposits are also associated 100 with the recent wastage of the Casement Glacier and are, therefore, probably later than Price's "Upper Gravels". The greatest bulk volume of the Seal River Formation, or modern outwash, south of "The Nunatak" i s composed of reworked older Hypsithermal gravels (Van Horn g rav els). These gravels could be seen being reworked by subglacial streams under the Plateau Glacier in earlier visits by the author and were building numerous short-lived deltas into the head of Wachusett Inlet. The Seal River outwash has its counterparts in all arms of Muir Inlet wherever modern streams are draining valley glaciers or are reworking the older outwash spreads (Fig. 37). As the termini of present glaciers continue to retreat, they are depositing within and on top of the Seal River outwash a carpet of bouldery ablation debris (Fig. 38). This is best seen along the margin of the Casement, P lateau, and Burroughs G laciers. An e sp ecially good example is seen along the terminus of the Casement Glacier where downwasting has caused lateral spreading of morainal material and also shears have developed a pattern of concentric concave ridges near the snout which are adding to the ablation mass. The last material to be deposited from the ice in the McBride Remnant area was a blanket of ablation debris. 101 Figure 37. Looking north up the McBride Remnant River toward Van Horn Ridge. This braided stream is inset into the Upper Van Horn gravel, carrying outwash equivalent to the Seal River Formation. As this area is being uplifted at about 4 cm/year, downcutting is rapid. Since the late 1940's, the stream has abandoned two channels as deep as this one, which are located to the east or to the right. 102 Figure 33. Looking north across the bouldery ablation blanket which covered the McBride Remnant ice block in 1964, Note ablation blanket which surrounds the ice and is being buried by sand from Coleman Creek a llu v ia l fan (A). FEATURES OF NBOGLACIAL ICE In determining the direction of Neoglacial ice movement, a number of re la te d features were studied. They include t i l l fab ric, grooved till, drumlins, crag-and-tail features, and striae. Figure 39 is a plot of all these directional features. Till Fabric Till fabric analyses (Fig. 40) were made mostly in the Neo glacial Glacier Bay Formation, because there are few Late Wisconsin (Muir Formation) exposures to work with. Also, fabrics in grooved-till ridges in the McBride Remnant area were studied by digging one-meter pits on the crests of several drumlin ridges in an attempt to get be low the zone of frost disturbance. Pebbles selected for fabric study had a long axis, ranging from 3 to 10 cm in length, which generally was about three times greater than the shortest axis. The strike of 100 pebbles was measured to the nearest five degrees, and dip directions were recorded. The average direction of pebble orientation and the dips to the north indicate that the last ice invasion, which deposited the Glacier Bay Formation, moved across the McBride Remnant area from N 25® W (Fig. 40). Fabrics in the Muir Formation had a more westerly orientation, with an average direc tion of N 60® W, Fabric analyses also show that the direction of Late Neoglacial ice flow was parallel to ridges of grooved till (drumlinized) 103 104 RIGGS GLACIER f WACHUSETT INLET LATEAU i J MU FS ? 1 î KILOMfTKRS y CRAC-a-TAIL y FABRIC y STRIAE / DRUMLINS MORSE û ROCHE MOUTONNEE Figure 39. D irectional features related to Neoglacial ice, Muir Inlet. Figure 40. Fabric analyses from Glacier Bay Till Explanation: 3L Till exposed in the longest east-west gully between Van Horn Creek and Canyon Creek IH Till exposed in North Creek on north side of "The Nunatak" IM Till in a one-meter-deep pit on 3rd drumlinized groove east of the northernmost of the chain of small lakes east of "The Nunatak" IL Till on axis of grooved till ridge immediately east of the southernmost of the chain of small lakes east of "The Nunatak" 3A T ill on f ir s t grooved t i l l ridge east of the McBride River. Fabric made in a one-meter pit lA Till on south side of Goose Cove Creek, about 1 km from its mouth 1C Till at top of high bluffs, 1 km south of Goose Cove Creek IE Till at headwaters of Forest Creek, 2 km above Forest Creek Gorge 2D Till on north side of Forest Creek, about 1 km east of the mouth white = rose diagrams show direction of orientation of pebbles, azimuths are to nearest five degrees black = direction of dip of pebbles. 105 106 3 L IH IM S SS Figure 40. FABRIC ANALYSES FROM GLACIER BAY TILL 107 in the McBride Remnant area, since the long axes of pebbles in the till were oriented parallel to the long axes of the ridges. The dips of pebbles were predominantly north and were at low angles. The up-glacier dip suggests it may be the result of movement of basal ice along flow planes that were inclined up-glacier at moderate angles or the accretion of basal till. The absence of prominent transverse patterns in most of the till fabrics suggests that pebble transport by rolling along long axes was not important. Toward the eastern edge of the McBride Remnant area, fabric study indicated that ice moved across this sector from a direction N 10" W to N-S. The north-south direction of ice motion was interrupted in the Limestone H ills (Fig. 6) th a t flank the east side of McBride Remnant Valley as a re s u lt of numerous high bedrock knobs. Crag-and- tail features on the Limestone Hills reflect two directions of ice motion, one from the north to the south and another, less strong, from the northeast to the southwest (Fig. 41). Streamline G lacial Forms Grooved Till and Gravel On the east side of Muir Inlet, extending from McBride Glacier southward to Forest Creek, till and gravel deposits are molded into the form of narrow elongate ridges (Fig, 42). These ridges are also well developed on the west side of Muir Inlet, south of Wachusett Inlet (Fig. 43). They are drumlin-like and even where they have been covered by vegetation these parallel ridges are outlined by the alignment of the 108 Figure 41, Looking northeast across the Limestone Hills which are composed of the fo ssilife ro u s marine Black Cap Limestone. These rock knobs allowed for the deposition of tails of till on their lee (south) sides, giving rise to "giant" crag-and-tail forms as are seen in the foreground. Note the development of superimposed streams, as at (a ), which flow east-west across these hills, forming deep watergaps. Note also the intricate gullying of till on Van Horn Ridge (B) in the background. 109 Figure 42, Looking northwest across the McBride Remnant Valley. Note the drumlinized topography across the valley, accentuated by stream erosion. The deep gullies in the centerground at 1, 2, and 3 are abandoned channels of the McBride Remnant River, (A) Larsen Creek, (B) "The Nunatak", (C) Van Horn Ridge, and (D) Muir In le t. Figure 43, Drumlinized topography on the south side of Wachusett Inlet with intricate gullying, lower right. 110 trees. These ridges were produced by the most recent ice invasion since they are composed of the upper gravel member of the Van Horn Formation and the Glacier Bay Formation, The till is usually thickest near the axes of the drumlin ridges. In the McBride Remnant area, these p a ra lle l ridges are up to 1.5 km in length and range in height from 2.5 to 23 m eters, with an average height of 9.5 meters. The distance between ridges is not re g u la r, but ranges from 30 to 410 meters and averages 180 m eters. Ridge forms are long and narrow, being from 10 to 50 times their width. The ridges appear symmetrical in cro ss-sectio n , and th e ir form is locally accentuated by meltwater channels which have developed between many of them, d issectin g some, and to ta lly removing segments of o th ers. Nowhere in the McBride Remnant Valley was bedrock observed within the ridge forms except along the edge of Muir Inlet where a small rock outcrop is seen north of "The Nunatak". Similar "drumlinized topography" becomes more apparent in the valleys of the Plateau and Burroughs Glaciers as the ice continues to downwaste and disappear. Numerous small bedrock knobs, which were nunataks just a few years ago, can now be seen with a veneer of till and gravel forming a very smooth ramp slope on th e ir western sides (Stoss sides) and in some instances streaming downvalley on the lee sides. Thus, a combination of rock drumlins and drumlins of till and gravel have been developed. Similar features are beginning to appear on the north flank of the Bruce Hills. Ill Drutnlins A small area of rock drumlins and exceedingly well-developed till and gravel drumlins can be seen west of Hunter Cove and on the south side of Wachusett Inlet, approximately 4 km west of its mouth (Fig. 43). Here, the forms are steepest on the west, which is the direction from which the ice advanced in this area, H. E. Wright, Jr. (1957) has suggested that the preferred up-glacier dip of pebbles at moderate angles is connected with upward-rising shear planes in basal ice. He has also suggested that perhaps drumlins are formed by a combination of the movement of debris along shear planes dipping u p -g lacier and longitudinal vertical flow layers tending to localize the deposition. The consistent up-glacier dip of pebbles seen while making fabric analyses suggests th a t perhaps th is was the case in the McBride Remnant Valley, Crag-and-Tail Features The crag-and-tail features in this region consist of either a knob of resistant bedrock or, more commonly, an individual boulder with an elongate body of t i l l streaming outward on the lee side. These features are common throughout the McBride Remnant area, and th e ir trend, for the most part, parallels that of the grooved till and gravel ridges which have been referred to previously as "drumlinized topogra phy", Where measured, the tails of till that stream outward in the lee of boulders were found to be from 30 to 90 meters in length, from one- half to one meter in height, and one to three meters in width (Fig. 44). 1 1 2 8 / < £ ^ CREVASSE FILLINGS CRAG-i-TAIL O PLANE TABLE STATION CONTOUR INTERVAL 5FT ?.. ^ JÎ2_ SCALE IN FEET G HASELTON, I964-I.PS. Figure 44. Plane table map of crevasse filling ridges and crag- and-tail ridges just northeast of "The Nunatak", Muir Inlet, 113 The lengths, widths, and heights of the tails are a function of the size of the bedrock knobs or the boulders that provided an obstruction within the ice, which in turn caused pressure melting and a hole into which the water-saturated till could move. It is estimated that on the flanks of Middle Mountain, the first ridge north of Red Mountain (Fig, 6 ), one t a i l extends outward from i t s crag (a large boulder) approximately one kilometer. Detailed measurements of crag-and-tail features made one kilometer northeast of "The Nunatak" demonstrated that the spacing between the ridges or tails ranged from 1.5 to 4.5 meters and averaged 2.3 meters. There is no regularity to the spacing, but it is apparently a function of boulder or cobble size which was sufficient to maintain voids on their lee sides for the development of the streaming of till down ice. Just east of "The Nunatak", near a chain of small ponds, crag- and-tail features suggest a slight convergence of the ice. West of the ponds, these features have a bearing that ranges from N 30° W to N 45° W, whereas east of the ponds they bear N 20° E to N 30° E. Along the eastern margin of the McBride Remnant Valley, crag-and-tail features and grooved till have a north-south bearing which confirms the fact that past ice motion was over the top of Van Horn Ridge and southward into and across the McBride Remnant Valley. These crag-and-tail features give the till plain surface a fluted aspect (Fig. 42), almost like plowed ground. It would appear as i f the t a i l s have been formed by debris th a t had been pressed up into channel cavities under the ice on the lee sides of the boulders. J, L. Dyson (1952) thinks that these parallel ridges represent filling 114 of subglacial tunnels that formed in the lee of boulders. He reasons that the weight of the overlying ice forces material upward into the tunnel making a ridge. The moraine surface is then a cast of the grooved base of the ice. He found that tunnel formation, in some cases, occurs beneath actively moving ice with a thickness of 60 meters. In 1963, the relict features observed by the author at the base of the McBride Remnant ice block were still under 20 meters of ice. By crawling under the ice block, small crag-and-tail features could be seen and their formation may be similar to that described by Dyson. G. Hoppe and V. Schytt (1953) have suggested two modes of forma tion of fluted moraines: (l) the surface of the ground moraine can be grooved by the uneven lower surface of the ice or by pebbles and boulders imbedded in the ice; and (2) debris can be pressed up Into channel cavities within the ice. Their evidence supporting the second idea is that ridges or tails often terminate at a boulder that is fixed in the surface of the moraine. If the ice is not too thick, long channels In the ice appear in the lee of the boulders owing to the plasticity of the ice. In 1963, V. Schytt published an extremely informative article dealing with fluted morainal surfaces. His main points were as follows: The so-called crag-and-tail features are depositional, as far as the ridges are concerned. The ridges have a more or less constant height over considerable distances, ranging from tens to hundreds of meters. Fluted moraine features are accumulation phenomena not re la te d to running water. He believes that the ridges are probably caused by a continuous supply of fluid till pressed into cavities formed in the lee 115 of boulders which are fixed solidly in the substratum. He observed that the ridges keep an astonishingly constant height even far out from the front of the glacier. This indicates to him that the cavity filling can hardly remain in the fluid state after it has been pressed upward into the cavity behind the boulder. If it remained fluid, the ice pressure would lower the roof and the morainal tail behind the boulder. It is thought that the fluid till, which is originally at the pressure melting point, is frozen to the basal ice because of the re lease of pressure when it is pressed up into the cavity. The debris is then carried along with the ice, and fresh debris from the sides, and coming down with the moving ice is co ntinually pressed into the lee of the boulder and is added to the previously frozen cavity filling. In th is way, the ridge being b u ilt up from behind the boulder is b u ilt forward as a p art of the moving g la c ie r u n til i t reaches a zone where low winter temperatures extend through the ice into the ground moraine. At this point, the ridge freezes to the substratum and is no longer able to move with the ice, which from then on slides over the ridge. Now there is a solidly frozen till ridge between the initiating boulder and the outer stranded end of the ridge; this means that a cavity is no longer able to form behind the boulder, and the formation of the ridge comes to an end. Schytt believes that such an explanation accounts for the parallelism of the direction of movement of the ice, as well as for the constant height and considerable length of the individual ridges. He noted a preferred pebble orientation parallel to the ice movement in four of the ridges studied. In the winter of 1962, Schytt and his 116 associates dug a 60-meter tunnel into the Isfallsglaciaren at Kebnekajse, Sweden, and noted th a t the p a ra lle l t i l l ridges extended the entire length of the tunnel. Several pebble fabric studies were made in crag-and-tail ridges near the west side of the McBride Remnant Valley northeast of "The Nunatak". In this area, the majority of the pebbles were parallel to the strike of the ridge in which they were found. S tria e Striae on Sealers Island bear N 5° W, and on bedrock hills just east of this island most striae have a bearing close to N 10° W (Fig. 39). This reflects the direction from which the main ice stream moved southward, down Muir Inlet, At higher elevations, such as the top of "The Nunatak", Red Mountain, and Van Horn Ridge, striae direc tions are close to north-south. On the west side of Muir Inlet, just north and west of the Westdahl Hills, the direction of striae range from N 60° W to N 70° W which demonstrates the convergence of tributary ice feeding into Muir Inlet from the north side of Minnesota Ridge and through a gap near the southern terminus of White Thunder Ridge. Figure 39 shows the d ire c tio n s of s tria e measured in Upper Muir I n le t. Thickness of Neoglacial Ice Early mapping and photographs give a basis for estimating the minimum thickness of the downwasting and retreating ice in the Muir Inlet area. Some of the earliest and most accurate data were compiled 117 by G. F. Wright in 1886, and by H. F, Reid and H. P. Cushing during th e ir mapping in Muir Inlet in 1890. From th e ir maps, some in tere stin g figures can be obtained. The terminus of the Muir Glacier was then about 36 km in advance of its 1965 position (Fig. 45). The terminus during the summer of 1890, was about 1-1/2 km north of station "Bull". The following comparisons are all based on the thickness of the glacial ice during the summer of 1890, and are taken from H. F. Reid. Where the mouth of Wachusett Inlet joins Muir Inlet, the ice was about 520 meters thick. In the middle of Upper Muir Inlet, just west of "The Nunatak", the ice was in the order of 650 meters thick, and all of White Thunder Ridge was buried by at least 100 meters of ice. The McBride Remnant Valley was then covered by about 450 to 600 meters of ice, and all but the highest peak on the east end of Van Horn Ridge was buried. J u st the highest p art of McConnell Ridge was v isib le as a nunatak, and Red Mountain, Coleman Peak, and Sitth-gha-ee Peak were large nunataks surrounded by Casement and Muir G lacier ice. Where the terminus of Muir Glacier is today, there was approximately 750 meters of ice above sea level. There are no depth figures for Muir Inlet at th is p o in t, but extrapolating from known depths, one can in fe r th a t i f the depth of the inlet here is 300 meters, then the total ice thickness would have been in the order of 1050 meters. Striations that were made by Neoglacial ice occur on the summit of Red Mountain at an altitude of 1220 meters. This indicates that Neoglacial ice reached altitudes at least as high as this in this part of the Muir In let area, W. S, Cooper (1937, p 43) found evidence for Neoglacial ice thickness farther south. He said: Figure 45. Looking northwest across the Muir Glacier Basin from the west shoulder of Mount Wright. Photograph taken by H. F. Reid, August 19, 1892. Note that Van Horn Ridge (l), the Curtiss Hills (2), and White Thunder Ridge (3) are submerged. Minnesota Ridge is at (4), the position of "The Nunatak" would be at (5). The terminus of Muir Glacier is in the lower left. CD 119 As to the maximum extent of the ice and its thickness at various points, a satisfactory estimate may be made, by using principally vegetational evidence. The advancing g la c ie r n atu rally swept away the forest clothing the moun tain slopes, and on the east side of the lower bay it left the lower edge of the undisturbed portion as a sharply defined 'high-ice mark', which was noted by several of the earlier observers. The northernmost point of the undisturbed forest, three miles south of Mt. Wright, marks the inter section of the southward-sloping ice surface and timber line, at about 2500 feet (762 meters). To the south, the lower limit of the old forest gradually descends, until at the end of the mountain mass just north of Beartrack Cove it stands at less than 1000 feet above sea level (300 meters). The gradient of this portion of the ice surface was about 17 feet (5 meters) per mile. He further indicated that ice was as high as 760 meters on the west side of Mount Wright. This was later confirmed by F. C. Ugolini (1966). "The Nunatak", which is 367 meters above sea lev el, f i r s t appeared through the ice between 1910 and 1911. At this time, there was still approximately 300 meters of ice over the McBride Remnant area. From photographs taken by the U.S. Navy Survey Expedition in 1929 (Fig, 46), it can be seen that the Muir Glacier's terminus extended from "The Nunatak" across to the Westdahl H ills which were s t i l l half buried in ice. At this time, McBride Remnant Valley ice was actively flowing into the head of Nunatak Cove and calving there. "The Nunatak" was completely surrounded by ice up to an elevation of 120 meters above sea level. A mass of dirty basal ice extended across a low saddle from Nunatak Cove almost to Goose Cove, and the low col in the middle of Van Horn Ridge s t i l l contained a tongue of ice from the McBride G lacier. Ice from the main Muir G lacier stream s t i l l extended over into the McBride Remnant Valley. Figure 46, Oblique air view of the Upper Muir Inlet region taken in 1929 by the U.S. Navy Alaskan Survey Expedition. Westdahl H ills (a), White Thunder Ridge (b), Mt, Brock (c), McConnell Ridge (d), Van Horn Ridge (e), McBride Glacier (f). Note dead ice s t i l l in the col of Van Horn Ridge. Black Mountain (g), Coleman Glacier (h), "The Nunatak" (i), Nunatak Cove {j}, Goose Cove (k). The small black dot in Goose Cove is a 50-foot boat. The terminus of Muir Glacier extends from (a) to (j). ro o 121 From the study of photographs taken in 1935, ice about 150 meters deep appears to have been l e f t over the McBride Remnant area. The term inal position of Muir G lacier had changed very l i t t l e since 1929, having retreated about 0.75 km. Approximately two-thirds of "The Nunatak" was surrounded by ice which extended up to about 90 meters above sea level on its northwestern end. Part of the segregated basal ice was still left in Van Horn Col, but was no longer connected with the McBride Glacier, All but the northern flanks of the Westdahl Hills were now exposed, and the highest peaks of White Thunder Ridge appeared as a group of separated nunatak knobs. In 1937, Muir G lacier had separated from the ice in the McBride Remnant Valley. After separation of the contributing mass of the Muir Glacier ice on the west, shrinkage and downwasting of the McBride Remnant Glacier was accelerated. By 1941, the Muir Glacier terminus had retreated as far north as Van Horn Ridge, The Westdahl Hills were completely separated from the ice, and yet ice was still banked up on the northeastern side of "The Nunatak" where it had been protected by avalanching, rockfalls, and flow of t i l l . At th is time, Coleman G lacier had separated from the McBride Remnant ice. The McBride Remnant Valley was s t i l l completely covered by ice. By 1950, only about one-half of the McBride Remnant area was covered by ice (Fig, 47), and much of it was protected by a blanket of debris from medial moraines. The thickness of the ice was approximately 30 to 60 meters at this time. The terminus of the Muir Glacier was Figure 47. Panorama of the McBride Remnant Valley and residual Ice looking east from the summit of "The Nunatak". Photograph taken the summer of 1950 by W, 0. Field, Numbers on the figure refer to: (l) east end of Van Horn Ridge, (2) Sitth-gha-ee Peak on the distant skyline, (3) Coleman Peak, (4) Middle Mountain, ( 5) Red Mountain. The rocks of the summit of "The Nunatak" appear in the immedi ate foreground, (6) Peaks south of Adams Inlet. N> r o 123 north of Van Horn Ridge, and was calving near the western base of McConnell Ridge. By 1958, the McBride Remnant ice had wasted considerably, and i t is estimated from distant photographs that only about one-fifth of the McBride Remnant area was then covered by resid u al ic e , and th is was confined to the northeastern and eastern parts of the region which had become heavily covered with ablation moraine. How thick the ice was at this time is not known by the author. The terminus of Muir Glacier could s t i l l be seen from the McBride Remnant Valley, and It had a ll but separated from the Riggs Glacier, Separation of Riggs and Muir ice took place sometime during the fa ll of 1960, as the author saw them still together in June of 1960. By the fall of 1964, only small, detached, masses of ice covered by gravel and ablation moraine were l e f t in McBride Remnant Valley. The largest of these, protected by a relict medial moraine, was 240 to 300 meters long, 90 meters wide, and 12 to 15 m eters thick (Fig. 48). By the Fall of 1964, the terminus of Muir Glacier could no longer be seen from the McBride Remnant V alley, and had disappeared behind White Thunder Ridge. The dimensions of the McBride Remnant ice block had shrunk con siderably by the summer of 1965. R. P. Goldthwait measured its dimen sions by pacing, and found it to be 110 meters long, 15 meters wide, and about 3 meters thick (Goldthwait, 1965). 1 2 4 B « y i •ILT CeVCH fk«AHftOMCb ft«0 «/ KAltg ■ O U L M Il* AND f M A S W t N T A CREVASSE FILLINGS » SMEAR RIDGES : g CRAG-AND-TAIL IC E BLOCK R g ] ABLATION RIDGES FORMED AROUND ICE BLOCKS \ r n ABANDONED LAKE ÎM L A K E 9, , . 190 290 390 Ago FEET SCALE CONTOUR INTERVAL 5 FT G HASELTON. l#64-hPS. Figure 48. Plane table map of ice-contact features and residual ice masses of the McBride Remnant Glacier, east of "The Nunatak". DEGLACIATION OF THE WcBRIDE REMNANT AREA Wasting of the McBride Remnant Ice Using old photographs, R. J. Price (1964) plotted the 1919 posi tion of the Casement Glacier. It was then about 0.8 km east of Muir Inlet, but Muir Glacier was still connected with the expanded piedmont lobe of the Casement Glacier, and the tidal terminus of Muir was at Sealers Island (Fig. 7). Between 1910 and 1920, Muir and Casement Glaciers separated. The ice th a t covered the McBride Remnant area become separated from the main Muir Inlet valley glacier in 1937. Photographs taken in 1941 in d icate th a t the McBride Remnant area was s t i l l covered by about 19 sq km of ice, except for a narrow strip along its western edge near Muir Inlet (Fig. 7). By 1948, the ice cover had been reduced to about 7.5 sqkm (Fig, 27). When the author first visited the area, in 1963, onlyabout 1 sq km of ice remained along the eastern edge of the McBride Remnant area (Fig, 7). Rates of Ice Wastage In 1948, the highest elevation on the McBride Remnant G lacier was about 180 meters above sea level. In 1963, the maximum elevation on the McBride Remnant ice, as determined by plane tab le mapping, was 84 meters above sea level. This represents 96 meters of downwasting 125 126 in 15 years, or 6,4 meters per year. W. 0, Field reported (1947, p 390) th a t from 1892 to 1929 ice downwasted in the Van Horn Col area a t the ra te of 4,5 meters per year, and th a t from 1907 to 1941 the rate of downwasting, southeast of "The Nunatak", was 6.7 meters per year (see map attached to Field's 1947 report). W. 0. Field has demonstrated that the rate of wastage of the Muir Glacier contrasts rather markedly with the stagnating masses in the lateral valleys near sea level. He found (Field, 1947, p 394) that between 1907 and 1941, Muir Glacier downwasted 11 meters per year, whereas from 1941 to 1946, its wastage through downmelting was accelerated to 30 meters per year. This in crease he noted was due to the flow of Muir ice to lower levels in the 1940's, L. D, Taylor (1962) noted changes in ablation with elevation on the Burroughs Glacier located on the north side of Wachusett Inlet and west of the Curtis Hills. From August, 1959, to August, 1960, the ablation around wooden stakes at lower elevations on the Burroughs Gla cier was 6.5 meters, whereas at higher elevations it was only 3.4 m eters. L ateral wastage a t the McBride Remnant ice block was determined by measuring distances to key boulders on the ice with tape and alidade. During the summer of 1963, the average amount of la te r a l wasting was 0.21 meter per day and the maximum amount recorded was 1,0 meter per day. Measurements were also made of lateral wasting between Flag No. 2 (north end of map on Fig, 48) and the ice edge (Figs. 49 and 50), The average lateral melting at this locality was 0.93 meter per day, with a maximum of 1.2 meters a day and a minimum of 0.12 meter per day. 127 Figure 49. North end of the McBride Remnant ice as seen from Flag 2 (see Fig, 48), July 29, 1963, Note ponded water around ice which accelerated wasting by calving. Till ridge just to the left of the ice block was formed the year before. Figure 50. Photograph taken on June 22, 1964, from same spot as th a t above, showing extent of downwasting and shrinking of remnant ice block, which can just barely be seen on extreme right. 128 Lateral ice wastage in this area has been accelerated by streams flowing along the edge of the residual ice blocks, and at times becoming ponded to form small lakes into which calving has taken place. R. P. Goldthwait (1966) in d icates th a t McBride Remnant ice has been r e treating laterally at rates varying from 40 to 50 meters per year. Drainage Changes During Deglaciation From about 1929 to about 1935, Goose Creek, south o f "The Nunatak", served as the principal meltwater drainage channel for the McBride Remnant ice along i t s southern and eastern boundaries. During this time, drainage was also entering Nunatak Cove under the ice, but it was not until between 1935 and the middle 1940's that the meltwater from the south and east sides of the McBride Remnant ice also began to flow westward. By 1948, air photographs indicate that Goose Creek no longer was the principal meltwater drainage channel on the south (Figs. 51 and 52). At th is tim e, most of the m eltwater from the remnant ice mass was flowing into Nunatak Cove from the McBride Remnant River. This same stream carries most of the drainage in the area today. North of "The Nunatak", drainage channels were probably esta b lished even when Muir Glacier ice was up against the western side of the McBride Remnant Valley, but the development of w ell-in teg rated channels came into being during the early 1930's. The main meltwater channels in the northwestern part of the McBride Remnant Valley are called, in this report. Canyon Creek and Van Horn Creek. During the 1930's, the 1940's, and into the early 1950's, both of these streams carried large volumes of meltwater which were adequate to cut channels 129 Figure 51. Goose Creek (A), which served as a principal melt water channel from the la te 1920's u n til the mid 1930*s. Wavecut platform at (B), Goose Cove rock drumlin in the foreground, and Nunatak Cove (C). Figure 52, Looking south from "The Nunatak" with Muir Inlet in the right background. Center foreground is an abandoned channel (Sun Creek) which was last used in the late 1940's. Dark line crossing it from l e f t to rig h t is the present channel of McBride Remnant Creek (see Fig. 6 for locations). 130 about 100 meters deep (Fig. 53). Today, there are still small streams flowing in these channels. Large gravel deltas developed at the mouths of both of these streams, but are no longer actively building outward. Marginal Drainage Channels An interesting series of small, discontinuous meltwater channels can be seen only a few hundred meters southwest of "The Nunatak" (Fig. 54), These mark the successive retreat positions of a remnant ice block that was melting away from "The Nunatak" on its east side. Whether or not these channels are annual cannot be demonstrated, no doubt some of them may have been. Two or more channels may be occupied along the margin of a dead ice mass during the span of just a few weeks. This sort of a situation was seen by the author along the margin of the Burroughs Glacier during the summer of 1960, A large, circular depression in the south-central part of the McBride Remnant Valley, east of "The Nunatak" marks the site of what was apparently an old moulin into which surface ice waters drained (Fig. 47). Many of the small, deep channels seen near the Gull Lakes (Fig, 53), a small chain of ponds northeast of "The Nunatak", were developing under the ice even during the 1940's The successive channels of the main meltwater streams that developed along the eastern side of Muir In le t, from the Klotz H ills northward to the present McBride G lacier, can be seen where large gravel deltas are now developed. Many of these deltas are inactive at the present time (Fig, 55), 131 Figure 53. Canyon Creek and i t s tr ib u ta r ie s which served as one of the p rin c ip a l meltwater channels for the McBride Remnant G lacier on i t s west. View is looking south across the McBride Remnant Valley from the summit of Van Horn Ridge. Gull Lakes a t (a). Figure 54, Small discontinuous meltwater channels at the lower left, outlined by snow, served as successive meltwater streams around a separate ice block which was situated southwest of "The Nunatak", Large braided stream in the foreground Is the McBride Remnant Creek. 132 Figure 55. Forest Creek d elta with Casement G lacier in the background. This is one of a series of deltas that extend southward to the Klotz Hills and are no longer building into Muir Inlet. The light- gray color on the right side of the delta is an invading mat of Dryas drummondi. 133 Eskers During downwasting of the McBride Remnant ic e , one large engla- c ia l esker system developed near the present mouth of Coleman Creek and extended for about 3 km in a southward direction, parallel to the pre sent McBride Remnant Creek. In 1964, th is esker was s t i l l ice-cored and was in the order of 20 meters above the surrounding ground moraine. I t was found to be composed of s tr a tif ie d sand and crudely bedded, cobbly gravel, and was covered by a bouldery blanket of ablation moraine debris. It appears to have formed near the base of the residual ice when there was little or no motion. Figure 56 shows an esker forming under somewhat similar conditions today, and Figures 57 to 59 are photo graphs of the large esker described above near Coleman Creek. Other very small eskers are found in scattered locations across the McBride Remnant Valley, but are most common along the eastern side of the Valley. Some are found up to 300 meters above sea level east of Coleman Creek. One was found to cross the top of a till ridge (Fig. 60), and was probably let down on the ridge as downwasting occurred. One was found to make a 90-degree change in direction from north-south to east-west, and became part of a till ridge indicating that some streams flowed w ithin the crevasses and developed washed sediments. The small eskers, where measured, ranged from 90 to 120 meters in length, 1 to 3 meters in width, and 1 to 2 meters in height. The small discontinuous eskers along the eastern edge of McBride Remnant Valley are in many cases associated with lake sediments or are found crossing small ponds that are still surrounded by ice. These 134 Figure 56. Ice-cored esker emerging from the snout of the active McBride G lacier. 135 Figure 57. Ice-cored esker and katnes and McBride ice block in left background. Note strong development of crevasse filling ridges running from left to right across the valley. East side of McBride Valley. Figure 58. Ice-cored esker and ablation blanket of dioritic gravel, east side of McBride Remnant Valley. Man for scale holding survey rod (a). 136 Figure 59. On top of ice-cored esker on east side of McBride Remnant Valley with development of kettle hole. White mound in back ground is 60 meters high. ■ Figure 60. Low gravelly esker developed between till ridges near the head of Canyon Creek, Notebook and trenching shovel for scale. The large angular boulders are part of the blanket of ablation moraine. 137 may represent subglacial and englacial streams that probably entered lateral, ice-dammed ponds allowing for aggradation to take place in the subglacial channels. An unusually fine thin-bedded sandy esker was seen on the sur face of the Muir Remnant Glacier west of White Thunder Ridge (Figs. 61 and 62), This is an example of englacial development. Collapse fea tures in the bedding could be seen due to downwasting of the ice beneath it. H, E. Wright and R. V. Ruhe (1965, p 35) have suggested that as ice thins and stagnates during wastage, the hydrostatic pressure is reduced or lost by air intake through, crevasses or other openings, and streams change from erosion to deposition, forming eskers in or around the previously eroded channels. This may account for the eskers that are developed in areas where there were no lakes into which the streams debouched. W, V, Lewis (1949) believed that movements of collapse, even in a relatively stagnant glacier could block tunnels and cause water to be diverted into new channels, leaving the old channels choked with debris. Two large esker systems, formerly ice-cored, exist in front of the Casement Glacier and extend down the old main meltwater drainage channels toward Muir Inlet (Figs. 63 and 64). Details concerning these esker systems may be seen in publications by R. T, Price (1964, 1966). 138 Figure 61, Sandy ice-coxed englacial esker and channel which developed within the Muir Remnant Glacier, Note slumping and destruc tion of bedding. Figure 62. Same esker as above, showing man for scale. 139 Figure 63, Dissection of esker system by the Seal River, south of the Casement Glacier. Parts of the eskers were still ice-cored in 1964. Figure 64. Bouldery esker covering a crag-and-tail ridge southwest of the Casement G lacier. S trandlines from a lake impounded by the esker seen in the left background. 140 Karnes Groups of small mound-like hills composed of thin-bedded well- sorted sands are scattered throughout the eastern and southeastern p arts of the McBride Remnant Valley. These are kames and kames associ ated with small eskers. Several were still ice-cored when trenched in 1964, and were composed of fine- to medium-grained sand and were found amid small square-shaped ponds that had developed between transverse till ridges. These can be seen in the process of formation in photo graphs taken during 1950 where streams were washing sands against the edges of masses of dead ice. In the southeastern part of the McBride Remnant area, where a lake had been in existence since the late 1940's, sands and gravels continued to build out against dead ice, forming kames. In the northwestern part of the McBride Remnant Valley, streams walled by ice and open to the sky were carrying sands into a lake which was drained by Canyon Creek. This can be seen in old photographs taken by W. 0. Field, and on file at the American Geographical Society. It is entirely possible that during the late 1940's and very early 1950's kames were formed in the ice in conjunction with such ice-walled streams and moulins. A very well-developed ice-cored kame, still 13 meters above its base in 1964, could be seen near the south end of the McBride Remnant ice block (Fig. 65 and map, Fig. 48), Kame deposits were seen at the head of the South Fork of the Muir Remnant River in 1963 and 1964 (Fig. 66). These were becoming exposed as the Muir Remnant ice retreated, and it appeared as though these deposits may have developed at the base of moulins. The very tops of 141 Figure 65. Ice-cored kame with stratified sand and pebbly gravel covered by ablation debris, east side of McBride Remnant area. Middle Mountain in the background. Figure 66. Moulin-kame emerging from the terminal portion of the Muir Remnant Glacier. Note moulin development in the background. 142 sandy kames were seen at the south end of the Burroughs Glacier in I960, and were photographed by the author in 1964 as they appeared super imposed on the ice (Fig. 67), Residual Movement of Remnant Ice After its separation from the Muir Glacier, the McBride Remnant ice continued to have a slight residual flow until thinning prohibited fu rth e r movement. Evidence for th is resid u al flow was reported by W. 0. Field (1947, p 390). He stated, "Local crevassing east of Anchor age Cove (Nunatak Cove) indicates that there has been lateral movement of ice into this depression. The migration from their original posi tions of the medial moraines which formerly extended down-glacier from Van Horn Ridge and the slopes of Coleman Peak also in d icates the slow creep of this ice mass". Further evidence noted by the author was the reverse direction of crag-and-tail features at the north end of "The Nunatak". From the photographic record, it is known that ice at this location moved from northwest to southeast, yet the crag-and-tail ridges extending outward from individual diorite boulders demonstrate that ice la te r moved from the southeast toward the west and northwest (Fig. 44), following the steep gradient toward Muir Inlet. Such changes in flow direction of stagnant ice masses are not uncommon, and have been demon strated to have occurred around the flanks of the Burroughs Glacier (L. D. Taylor, 1962). 143 ■*r: Figure 67. Ice-cored kames at south edge of Burroughs Glacier, 144 Minor T ill Ridges Throughout the McBride Remnant area, a system of long narrow transverse ridges is well developed. Few of these ridges exceed a height of 2 meters. They are composed mostly of till, and can be differentiated genetically into crevasse fillings, shear plane ridges, and ic e -d lsin teg ratio n ridges. Crevasse Fillings There is a network of crevasse filling ridges both north and east of "The Nunatak", and to the south and west (Figs, 68 and 69). The network of these ridges in the southwest, between Forest Creek and McBride Remnant Creek, are now to ta lly obscured by thick alder and willow vegetation; those to the north still stand out in bold relief, A comparison of these ridges with the earlier crevasse pattern of the McBride Remnant G lacier, seen on the 1948 a e ria l photographs, shows a very strong similarity. Furthermore, these ridges could be seen developing from crevasses in photographs taken in 1950 and in 1954, Figure 70 is a plane table map diagrammatically showing part of the network pattern of these crevasse filling ridges. There are two sets of ridges, one set overlying the other, so that the upper set crosses the lower set at angles varying from 90 de grees to 10 degrees (Fig. 71), Both sets of ridges lie on top of crag- and-tail and grooved-till features. Part of this ridge pattern can be seen on the plane table map of Figure 48. 145 Figure 68. Looking west across McBride Remnant area. Note pattern of bifurcating crevasse filling ridges within the snow. Red Mountain alluvial fan in the foreground and dead ice just beyond. Figure 69. Crevasse filling and shear-plane-till ridges extending outward from the McBride Remnant ice block. 146 ^ £ 5 MELTWATER CHANNEL CRAG-a-TAIL GROOVED TILL ' CREVASSE'FILLING-RIOSES O PLANE TABLE STATION 0111 , ®P 1^0 'SO SCALE IN FEET G. HAS ELTON. 1 9 6 4 -IPS Figure 70. Plane table map of crevasse filling ridges developed on a drumlin ridge east of "The Nunatak". 147 Figure 71. Crevasse filling till ridges east of "The Nunatak" 148 Toward the northeast corner of the McBride Remnant area, ridges are higher and can be traced more continuously. This is p artly due to the youth of the ridges here, as they have emerged from the ice only within the last few years. Most of these minor ridges are com posed of till having the same composition as the ground moraine and contain boulders or cobbles (Figs. 72 and 73). A few of the ridges are composed of s tr a tifie d sand and gravel, indicating washing by streams. Where erosion has not dissected them, the ridges can be traced continuously for as much as 0.8 km. Breaks in the ridges are usually the result of stream erosion. The highest ridges range from 3.6 to 8,0 meters (Figs. 74 and 75), but the m ajority are about one meter in height. Their width varies from a few centimeters up to 9 meters. The average strike of the .ridges is N 70® E, but their range is considerable, varying from N 40® E to E-W. The distances between the ridges are quite variable, ranging from 3 meters up to 150 meters, but the average was 24 meters. The best area for their study is in front (east) of the rapidly downwasting Plateau Glacier. Here they are in abundance and are found in a maze of criss-cross patterns. They can be seen emerging from the crevassed terminal portion of the Plateau Ice (Fig. 76). Here there Is strong support for their mode of development and they consist of the same water-saturated ground moraine till. There appears to be little material that is dropped into the crevasses, but more of a squeezing of the till into the fractures when the ice is extremely thin. 149 Figure 72, Cross-section of crevasse filling ridge showing crudely bedded, coarse sand. McBride Remnant V alley ea st of "The Nunatak". Figure 73. Crevasse filling till ridge east of "The Nunatak", Note absence of bedding but crude east-west fabric parallel to the ridge. Pencil for scale. 150 Figure 74. East side of McBride Remnant area looking north. Small "squeeze-up" till ridges crossing north-south crag-and-tail ridges. Note development of square ponds. Dead ice in right middle- ground. Figure 75. One of th e la rg e r t i l l - r i d g e s west of the McBride Remnant ice block. 151 Figure 76. Crevasse filling squeeze-up till ridge forming along the margin of the Plateau Glacier. Note flow-till apron being washed, and size of fragments released from crevasse. Stream flowing from moulin is dissecting the ridge. Also note the very top of ridges appearing from crevasses in the background. 152 Shear Plane Ridges Other minor ridges found near ice blocks in the McBride Remnant Valley have developed as a result of material which was being released from steeply dipping till-rich shears. These ridges could be traced directly into the shear itself. Some of the material released from the shears formed flo w -till mud fans which became covered with angular blocks of ablation debris, while others formed distinct, but discon tinuous ridges (Figs. 77, 78, and 79). Many of the shear plane ridges that were observed in the process of formation are asymmetrical when formed. They are steep on the south, or lee sides, with an angle of repose varying from 50 to 60 degrees, and are gentle on the north, or stoss side, with an angle of repose varying from 10 to 12 degrees. During melting, the material in the shear absorbs more heat, and in time a recess develops along the plane of the shear. Meltwater flowing down the trace of the shear also en larges the re-entrant. The material which is released from the shear plane moves down the plane in this re-entrant or "chute", following the angle of the shear itself. The shear plane becomes the gentle, or stoss slope for the material which is released. The overhanging ice, above the shear plane, acts as a barrier as the material is released, causing it to turn as it rolls, slides, or flows down the steeper lee slope. The surface of these shear plane ridges is generally covered by a blanket of angular ablation boulders which drop off the sides of the melting ice block onto the top of the ridges. 153 Figure 77. Till being released from squeeze-up into shear, forming a mud-flow ( t i l l ) fan at the base of the McBride Remnant ice block. Figure 78. Close-up of a till squeeze-up at the top of the McBride Remnant ice. 154 Figure 79. Till-filled shear (squeeze up) on east side of the McBride Remnant. Ice block covered by angular boulders from ablation d eb ris. Note size of ice c ry sta ls behind the man. Some were up to 30 cm long. 155 Ice Disintegration Ridges Small circular, oval, or irregular ridges (unlike the linear ridges) have formed around iso late d ice blocks which were separated from the main mass of dead ice (Fig. 80). These ridges are best devel oped around ice blocks that carry an excessive amount of ablation debris. This material slides off the blocks in all directions and accumulates in such quantities at the base of the ice blocks that the ridge form is preserved after the ice melts (Fig. 81). The ridge- forming material can also slide into fissures within the ice. Where these ridges do not completely close, it is because ablation debris was incompletely deposited around the ice margin. In some cases, the ridges have a crude pentagonal to hexagonal outline (Fig. 48), The irregularities in form reflect the shape or outline of the ice block around which they were deposited. In one small area, these ridges were concentric and occupied a small depression. The till around the edges of these wasting bodies of ice is so water-saturated that it will not support the weight of a cobble or boulder, let alone the weight of a man crossing it. It is common to sink up to one’s knees in this m a te ria l. C. P. Gravenor and W. 0. Kupsch (1959) have suggested th a t, once the ice has acquired a thin layer of ablation debris on its surface, further downwasting becomes very slow and the clayey nature of the till may be preserved. They have also suggested th a t the compactness of till can be the result, not of squeezing, but of the till's original 156 Figure 80. Circular, blocky ice-dlsintegration ridges, east side of McBride Remnant Valley. Figure 81. Gravel ridges forming around the margins of ice blocks at the western base of Red Mountain. Note washed ( s tr a tif ie d ) gravel deposit that has accumulated on top of the ice. 157 texture, structure, and fabric. They think that the character of till in ridges or in hummocky moraine cannot be used as strong evidence in determining the origin of the features. Work by 0. H. Loken and E. J , Leahy (1964) in southeastern Ontario on small moraines concludes with the assumption that ice ad vanced into a lake, was buoyed up, tension cracks formed, and morainal material was squeezed up into the fractures. J. I. Andrews and B. B. Smithson (1966) have discussed the development of cross-valley moraines on Baffin Island, and conclude that they are caused when ice is grounded in a lake, or form at right angles to an ice cliff by the squeezing of till into basal crevasses or meltwater tunnels. The pattern of the moraines there is much the same as those seen in the McBride Remnant Valley. These ice-disintegration ridges are not as conspicuous as the linear ridges that have been described above. They seldom exceed one meter in height, and if they do, they are ice-cored or lie against the side of the block around which they are forming. For the most p art, the closed ridges consist of angular boulders and cobbles with few fines. Figure 82 is a map of the Muir In le t region, showing the loca tion of the features discussed above that developed during and after downwasting of glacial ice. Theories for Ridge Development Work by G, Hoppe (1952) has attempted to demonstrate that dead ice features are the result of basal till that has been squeezed into Figure 82, Map of glacial and postglacial features, Muir Inlet, Explanation: }^V^-vDelta Alluvial fan ^ Lake Abandoned meltwater channel Present streams — Waterfall 24 Measured stratigraphie section A Old Coast and Geodetic Survey S tation Current position of glaciers • • • • Moraines Crevasse filling ridges Shear plane ridge Esker Circular crevasse ^ ^ 0 Crag-and-tail ----- Shear moraines Kame Till mud flow Contour interval ICC up to 500'; above 500', interval is 500'. 158 159 Â KLOTÎ 160 openings on the underside of the ice. His conclusions are: (1) The till does not show any evidence of washing, as would be the case with superglacial m aterial that has falle n from the ice surface or from side walls into an open crevasse. (2) The till is compact and has all the characteristics of basal till. (3) The till contains pebbles and cobbles that show distinct fabric with their long axes oriented at right angles to the long dimension of the ridges. Hoppe regards this fabric as a primary characteristic caused by the lateral pressure of the ice blocks which squeezed the till up into the fracture. Most of these factors apply to the ridges that have been exam ined in the McBride Remnant area, although fabric may vary g re a tly due to flowage of the till during the time of its mobility and after development of the ridge due to frost heaving. Upon its release from the ice walls, some of the till is washed down the face of the ice or flows along as a soupy mass within the crevasse (Fig. 78). Such sec ondary transportation is shown to develop a fabric which may be parallel to the strike of the ridge. In summary, the ridges may form from m aterial th a t accumulates along the margins or between blocks of ice, or from till that is squeezed upward into subglacial openings. GLACIAL HISTORY A sequence of events is recorded by a rather complete stratigra phy in Upper Muir Inlet which spans the time from very Late Wisconsin to Recent. In Late Wisconsin a marine transgression is recorded in Muir Inlet and its tributaries by the Forest Creek Formation which may be, in part, as old as 14,000 years B.P. and, at the top, as recent as 10,500 years B.P. This marine invasion was followed by a last Wisconsin ice ad vance whose minimum age ranges from 10,900 to 10,500 years B.P. Prior to 7000 years B.P., glaciers were as far back as those of today. This is supported by the finds of trees in place well up Muir In le t which date th is old (Figs. 83 and 84) and re fle c t conditions as warm as today. Furthermore, trees of a climax forest in their growth positions are still appearing from beneath ice that is retreating, which indicates that prior to Late Neoglacial time glaciers were farther back than now. During the in te rv a l from about 7000 to 4000 years B .P., Muir Inlet and its arms were filled by outwash. Filling took place from many directions and intermittently buried forests that had become established on the outwash fill. This lower outwash marks the beginning and end of Hypisthermal time. D. McCulloch and D. Hopkins (1966) believe they have evidence for what they call an "early recent warm interval", which took place earlier 161 162 Figure 83. Stumps (7000 years old) in the Lower Van Horn gravel on the south side of Nunatak Cove, Figure 84. Remnant of climax forest buried in gravels on the south side of Nunatak Cove. Red Mountain appears between the stumps and the south end of "The Nunatak" is to the l e f t. 163 than Hypsithermal time in Glacier Bay Monument, This is based on radio carbon dates of trees, wood, and beaver sticks from the Kotzebue Sound area. This early warm interval is suggested to have begun 10,000 years ago, and lasted u n til 8300 years ago. This in terv al they c a ll pre- Hypsithermal time, a time of independent warming not connected with the later post-glacial thermal maximum that lasted approximately from 7000 to 3000 years ago. Their suggestion is, that as sea level rose to near its present position, the accompanying maritime climate lowered tem peratures along coastal portions of northwestern Alaska, while at the same time inland areas enjoyed the higher temperatures of a post-glacial thermal maximum. They consider recent time (Holocene) to have started 10,000 years ago. In Muir Inlet, it was the Hypsithermal outwash that eventually buried the climax forest, as the trees are still in their position of growth with the root systems firmly entrenched in the gravels or on bedrock (Fig, 85). These upright stumps show abrasion from stream cobbles and boulders. The trees are not found laid out in a line within the gravels or covered by t i l l s , nor are they badly mangled by ice where they appear upright within the gravels. Usually a forest mat of needles and twigs is seen around the stumps, together with a soil. This indi cates that during the time of early outwash filling there were no exten sive advances or retreats of ice in Muir Inlet, From a number of radiocarbon dates of trees in place, R. P, Gold- thw ait (1963) has shown th at Muir In let and i t s trib u ta ry arms were filled to sea level about 7000 years ago. He was also able to demon strate in Wachusett Inlet that this outwash (lower Van Horn member) had 164 Figure 85. Evidence that climax forest trees were buried in Hypsithermal outwash gravels (Van Horn Formation). Note sprawling root system fixed in gravels and the large abrasive cut by man's hand. Boulders here were wedged into the wood. (Upper Forest Creek) 165 reached 60 meters above sea level approximately 2200 years ago. By p lo ttin g radiocarbon dates from samples taken from tre e s in place in the outwash gravels against their elevations, he calculated the rate of inlet filling. His conclusions were that sediments accumulated in Muir Inlet at an average rate of 1.4 cm a year, with a minimum of 1,0 cm and a maximum of 5 cm a year. About 4500± years B. P. (Goldthwait, 1966b), ice may have been advancing from the high Fairw eather Range in northw estern G lacier Bay, This coincides with other advances at about this time (Meier, 1964) in western North America. This ice advance down Glacier Bay may have dammed Muir Inlet to create a lake (middle Van Horn member) which lasted about 2000 years, or from about 4200 ± 500 years B.P. to 2200 ± 200 years B.P. Evidence for th is is given by a number of dates above and below the lacustrine sediments (see Table 6) which demonstrate a common time of beginning and ending of lake d eposition, and by the fact th at lacustrine deposits are common to both sides of Muir and Wachusett Inlets. This ice advance down Glacier Bay is of Early Neoglacial time. A second episode of outwash filling which covered the lacustrine sediments signals the beginning of a Late Neoglacial ice advance in the Muir Inlet area. Radiocarbon dating of samples taken from trees that were overridden by ice indicates that Late Neoglacial ice advance was well under way in the Muir Inlet area by 3000 years ago. It was this advance that deposited the ubiquitous blanket of the Glacier Bay Formation (Late Neoglacial till). A date from an overridden tree north of Wachusett Inlet, on the west side of the Curtis Hills (Station 7, Fig, 6) at an elevation of 220 meters above sea level, demonstrates 166 that ice had already reached this position 2735 ± 160 years ago (Sample 1-122). On the west side of White Thunder Ridge, wood was found in place at an elevation of about 450 meters above sea level by W. O, Field (1964) and was dated at 2120 ± 150 years B.P. (Sample 1-1610). Wood from a log, not in the position of growth, but carried from above and buried in the lateral moraine of the McBride Glacier, was also about 2000 years old (Sample 1-58-11). A sample of wood in place, found rooted on bedrock at an elevation of 110 meters above sea level, on the north side of "The Nunatak" was dated at 1660 ± 110 years (Sample 1-1304). All of these dates demonstrate slow invasion by ice during the Late Neoglacial in Upper Muir In le t. Dating of stumps in place closer to the sources of the neve basins will give more precise information in the future as to the time of the initiation of Neoglacial ice invasion in this part of the National Monument. Near the present terminus of the Casement Glacier, wood buried by the G lacier Bay Formation was sampled and found to be 1400 ± 120 years old (Sample 1-1302). This dates the time of advance of the Case ment Glacier out of its own valley. R. P. Goldthwait (1965) reports having found wood in the position of growth about 600 meters above sea level on the west side of the Casement G lacier. The wood was in a paleosol on top of gravel and dates outwash f illin g in the Casement Valley just prior to the advance of Late Neoglacial ice. This location is about 5 km north of the terminus and the wood here is 2190 ± 105 years old (Sample 1-2302), This same ice advance, based on radiocarbon dating of logs, was moving into Adams In le t between 1500 and 1600 years ago (Goldthwait, 1965). G. D. McKenzie reports a date (1967) of 167 1980 ± 100 years B.P. (Sample 1-2394) from tre es in place some 20 meters below a till. R. P. Goldthwait (1965) estimates, "It took 400 years for Late Neoglacial ice to fill across the whole of Wachusett and Adams Inlet areas". Late Neoglacial ice advanced at least as far south as Bartlett Cove and may have reached into Icy Strait (Fig. 1). Here, it built a large conspicuous terminal moraine on which the buildings of the Park Service Facility have been constructed. The time of Late Neoglacial ice invasion in the Bartlett Cove region is given by the dating of a prone log which was buried in out wash sand on the flanks of the terminal moraine. This log was dated a t 285 ± 90 years B.P,, or from 1665 A.D. (Sample 1-2303). This moraine was produced by Late Neoglacial advance to Bartlett Cove and has been traced on both sides of the mouth of Glacier Bay to the northeast and northwest. Further evidence for the time of the climax of Late Neoglacial ice is given by D, B. Lawrence (1958, p 101) when he sta te s th at; On the shore of Bartlett Cove near the mouth of the Bay stand the youngest fossil groves of all, the wood well preserved even with the bark still in place below the surface of the beach from which the stumps protrude. Excavation revealed that some were rooted on horizontal logs of a previous forest, indicating that several centuries had elapsed since a previous g laciatio n had reached this far down the bay. Radiocarbon dating of this forest also by Preston, et al. (1955: stumps Y 132-83 and Y 132-86) and by Barendsen, Deevey, and Gralenski (1957: stump Y-308) shows th at these erect stumps were living tre e s less than 300 years ago; the tre e s were dated modern. But they stand at a level where trees could not possibly grow now. Some are indeed rooted among seaweeds between the tides at levels at least 20 feet below the most venturesome young spruces living along the adjacent shore today. Less than 300 years ago when the fo ssil stumps were living tre e s the ice advanced from 168 some unknown line of retreat to the mouth of the bay, overwhelming the forests as it moved ahead and depressing the land as the load of ice increased where none had been immediately before. The oldest tree that was cored by Lawrence in 1957 was found to be 121 years old. By similar ring counting, R. P. Goldthwait (1963) found trees 125 years old and H. F. Decker (1966) found trees 175 years old. The time of ice retreat has been suggested by H, F. Decker (1966, p 80). He states that if one assumes that a tree ring count of 175 years is correct, and that the same rates of recession prevailed in the region of Bartlett Cove as presently in Muir Inlet, and, further more, that the spruce started growing sometime during the beginning of what he terms the "closed thicket stage (V)", which is 30 to 35 years after deglaciatipn, then the Bartlett Cove region must have been de glaciated at least "205 to 215 years ago". Decker further states that if it takes 75 to 90 years for a spruce forest to develop, as his observations in Muir Inlet seem to indicate, and the average age of 10 felled spruce is 125 years, then, at least 200 to 215 years have elapsed since déglaciation. Therefore, 1765 is an approximate date of ice retreat here, and agrees amazingly well with W. S. Cooper's (1937) earlier estimated dates of retreat between "1735-1785". It is known from historic observations that this ice was still in the lower part of Glacier Bay in the late 1700's. Since then, Neogla cial ice has retreated about 70 km up Glacier Bay and into Muir Inlet. During the last 300 years it has retreated a maximum of 100 km from Icy S tr a it, a t the mouth of G lacier Bay, to i t s present p osition a t Grand 169 Pacific Glacier (Fig, l). For a calving ice front in sea water, this is the greatest observed recession anywhere in the world (Fig. 49). The mechanism for the essential instability of fjord glaciers has been discussed by J. H, Mercer (1961). Rapid retreat of glaciers is still continuing in Upper Muir Inlet now. Muir Glacier, which was still tidal in September of 1966, has receded 1700 meters since August of 1964 (Field, 1967). There are, however, several glaciers in Glacier Bay National Monument which are readvancing. W. 0. Field (1967) has generously made available some recent figures for advances of some of these glaciers. His records show the following: (1) Carroll Glacier was undergoing appreciable activity of the surge type when seen by Field in 1966, and he expects that there will be a change in the terminus this year, (2) The terminus of the Rendu Glacier in 1966 was 350 to 600 m eters in, advance of i t s po sitio n of 1964. (3) From 1964 to 1966, the terminus of the Grand Pacific Glacier advanced 140 meters. ( 4 ) The terminus of Tyeen Glacier in Johns Hopkins Inlet reached tidewater between April and July of 1966. ( 5 ) Between 1964 and 1966, the maximum advance along the front of the Johns Hopkins Glacier was 350 meters. (6) The LaPerouse Glacier is again advancing into the Pacific Ocean across what was a beach in 1965. Field has no data for the amount of th is advance. 170 The fact th a t surging on these g la c ie rs, as on other g la c ie rs throughout Alaska, has taken place repeatedly in modern time is indi cated by W. S. Cooper (1937). Following this ice retreat in historic time, vegetation has rapidly re-established itself so that an alder, willow, and poplar forest mixed in a "jungle-like" thicket is found within 4 km of the snout of some of the retreating ice masses. One of the best areas to study a succession of pioneer plants is in the Muir Inlet area. This has been done by W. S. Cooper, D. B, Lawrence, and most recently by H. F. Decker (1966). Detailed counts of plant types, species by species in 10-meter plots, were made by Decker in many regions including that of the McBride Remnant area and the interested reader is referred to thevery fine discussion of this in his report (Decker, 1966, p 76). Decker has summed up his most interesting observations in the Muir Inlet area in abstract form, and the below is a quote from his abstract. Plant succession in Muir Inlet, Glacier Bay, Alaska can be divided conveniently into eight intergrading stages: I, early pioneer, consisting largely of Dryas and Salix seedlings; II, mat stage, in which the Dryas forms exten sive mats 0.1 to 4 meters in diameter; III, late pioneer, in which the terrain has scattered alder, willow, and poplar shrubs; IV, open thicket stage; V, closed thicket stage; VI, poplar-line stage, in which poplar emerges above the alder canopy, forming a clearly discernible line on the horizon; VII, spruce forest; and VIII, spruce-hemlock forest stage. In the Muir Inlet region, the first three stages (I , II, III) occupy the deglaciated terrain for 20 to 25 years; 10 more years are required for the transition of open thicket (IV) to closed thicket (V). The poplar line (VI) along the east and west sides of Muir Inlet closely follows the 1920 positions of the McBride, Casement, and Plateau Glaciers, indicating it forms 40 to 50 years after deglaciation. It takes at least 75 to 90 years after déglaciation for a spruce forest (VIl) to supplant the alder-willow-poplar closed thicket (V). 171 In the McBride Remnant area the early pioneer vegeta tion stage (l) grades into the mat stage (II) within 5 years after deglaciation. The late pioneer stage (III) has a close correspondence to the 1940 position (then ice covered most of the McBride Remnant Valley) of the McBride G lacier or 20 to 25 years a fte r deglaciation--about the same amount of time required in the Casement Glacier region. The same is true of the advent of the closed thicket stage (V), which re quires approximately 30 to 35 years to form in the McBride G lacier Remnant region. Decker found the same time sequences to hold for the Wachusett- Hunter Cove area. Meltwater streams are once again rapidly filling the arms of Muir Inlet with post-Neoglacial (Recent) deposits. These deposits are seen as d e lta s and are most impressive at the times of low tide (Fig. 86), Just how fast delta building is being accomplished is not known to the author, but this is one area that needs study very badly. From d e ta ile d studies made by C. Cronk (Goldthwait, et a l . , 1963) on the delta which fronts the North Crillon Glacier in Lituya Bay, he found that between 1920 and 1961 the delta appeared and grew to 145 x 10^ cubic meters. Another interesting study was carried out by G. Hanson (1934) on the Bear River Delta at the head of the Portland Canal in British Columbia in the early 1930's. He gives some inter esting figures of rates of filling of the head of a fjord. The average rate of inlet filling from 1909 to 1927 was 30 feet (9 meters) per 7 year, and the amount of deltaic material contributed was 2.25 x 10 4 cubic feet per year, or 63 x 10 cubic meters. In Upper Muir Inlet, significant delta building is taking place outward from the McBride G lacier (Fig. 87) and can best be seen during low tide. Subaqueous deltaic sediments are also accumulating in front 172 Figure 86. Delta development a t the mouth of Goose Creek, Dark band below the gravels on the cliff, on the far side of the delta, marks the top of the middle member (lacustrine) of the Van Horn Formation, Figure 87. Delta developing at the terminus of the McBride Glacier. S-shaped deposit near ice edge is part of the eroded terminal moraine. 173 of the Riggs Glacier and probably in front of the Muir Glacier, as its northern end appeared to be aground in the 1966 photographs. Seal River, the major meltwater stream from the Casement Glacier should land-tie Adams Island in possibly one or two decades. In the years to come practically all of the inlet filling in Upper Muir In le t w ill have to come from Muir, Riggs, and McBride Glaciers, as there is no other significant filling going on until one reaches the Morse River. Wachusett and Adams Inlets should continue to fill, since many streams debouch into their arms from valley glaciers. Small lakes and ponds can be seen developing along the edges of the dead Ice masses and glaciers in the Muir Inlet area. The most extensive lake in the immediate area is the one which has been in existence at the west end of the Burroughs Glacier since the late 1950's (Fig. 88). A study by S. D. Hichs and W. Shofnos (1965) has shown th a t a maximum rate of land emergence of about 4 cm a year, relative to sea lev e l, is taking place at B a rtle tt Cove. They believe (p 3318) th a t this uplift is the result of rebound from present localized déglacia tion or possibly the combination of present localized and general post-Wisconsin deglaciation. C. Pierce (1960) has reported that from the period 1940 to 1959, the land in the Muir Inlet area has been rising at a rate of 3.5 cm a year relative to sea level. This uplift is demonstrated by tree stumps and rocky shoals that are continuing to appear from their depressed position below the high tide line. Tec tonic uplift must also be affecting the entire region, but its rate is not known. R. P. Goldthwait believes (1966b, p 11) that the most rapid 174 Figure 88. Lake at west end of Plateau G lacier, impounded against high lateral moraine of Carroll Glacier. 175 uplift is not taking place at Bartlett Cove, but in the neighborhood of the Klotz Hills. Here he found the rate of uplift is in the order of 4,5 cm per year. This means that the land around the Muir Inlet area is rising at the rate of 4,5 meters per century. This is accelerating stream downcutting and allowing for rapid removal of the unconsoli dated sediments. Raised beaches were not part of the author's study, but excel lent relict wave-cut benches can be seen wrapping around the Goose Cove rock drumlin at its sound end, on Sealers Island (Fig. 52), at Wachu se tt P o int, and along the east end of the C u rtiss H ills. Where measured, the wave-cut bench of Sealers Island and Goose Cove was 10 meters above high tide. The time of cutting of the wave-cut bench is not known. No organic m aterials were found th a t could be dated on the bench. From the work of C. A, Kaye and E. S, Barghoorn (1964), i t is in fe rred th a t sea level was higher 14,000 years ago than today. At that time wave cutting could have taken place as it is known that the marine Forest Creek formation dates from that time; however, this is an assumption that has not been demonstrated. SUMMARY The purpose of the 1963 and 1964 field studies was to determine the glacial history and to study the development and possible causes of the various g lacial features in Upper Muir In le t, These studies were carried out under the auspices of the National Science Foundation. The stratig ra p h ie succession in Upper Muir In let represents deposits of Late Wisconsin to Recent time, and includes from oldest to youngest: Late Wisconsin: Forest Creek Formation and Muir Formation (Till) Hypsithermal: Lower member of the Van Horn Formation Early Neoglacial: Middle member of the Van Horn Formation Middle Neoglacial: Upper member of the Van Horn Formation Late Neoglacial: Glacier Bay Formation (Till) Recent: Seal River Formation. Till lies beneath the Forest Creek Formation in Adams Inlet and is known to be older than 10,900 years B.P. Between 14,000 and 10,000 years B.P., marine deposits accumulated in Muir In le t, i t s trib u ta rie s , and in G lacier Bay. These deposits are represented by the fossiliferous Forest Creek Formation. The Muir Formation, the older of two t i l l s in Upper Muir In le t, lies above the Forest Creek Formation and is more indurated and wea thered than the younger till (Glacier Bay Formation). It represents 176 177 the latest Wisconsin ice advance. Peat beneath the Muir Formation dated 10,400 years B.P, The Van Horn Formation represents three episodes of inlet f il l i n g . A basal outwash (lower member, Van Horn Formation) records filling during Hypsithermal time when the climate was as warm or warmer than today. Trees near sea level have been dated 7000 years B.P. and record a climax forest that grew across this lower outwash and subsequently was buried by the outwash. By 4000 years B.P., Early Neoglacial ice had advanced down Glacier Bay and dammed Muir Inlet creating a lake which lasted for about 2000 years. Accumulation of la c u strin e d ep o sits in Muir In le t (middle member, Van Horn Formation) was brought to a close by Middle Neoglacial outwash (upper member. Van Horn Formation), which probably reflects a change to cooler and moister conditions. The ice advance, which had started in the mountains surrounding Muir Inlet in Late Neoglacial time, reached the upper part of Muir and Wachusett Inlets by about 3000 years ago. This is the ice that advanced to Bartlett Cove in the 1600's and deposited the Late Neoglacial till (Glacier Bay Formation). Ice was retreating from the lower reaches of Glacier Bay in the middle to late 1700's. Since that time, it has retreated out of lower Glacier Bay and up Muir Inlet about 75 km. Vegetation is once again re-establishing itself in a recogniza ble chronological sequence throughout the deglaciated Muir Inlet area. Muir In le t and i t s trib u ta r ie s are once more being fille d by modern 178 outwash (Seal River Formation) and a thin blanket of ablation moraine covers much of the Glacier Bay Formation. Small ponds and lakes are developing along the margins of dead ice masses (Fig. 89). Uplift from ice unloading that started in the Late Wisconsin is continuing today. The maximum rate of land emergence relative to sea level has been reported at both Bartlett Cove, 4 cm a year, and in the vicinity of the Klotz Hills, 4.5 cm a year. Till fabric, streamlined glacial forms, striae, and past aerial photographs are helpful criteria for determining past ice directions in Muir Inlet. All of these indicate that ice advanced into the McBride Remnant area from the northwest and north with very local feeding from the east. The advances in Wisconsin and Neoglacial times were naturally influenced by the orientation of the inlets. Between 1890 and 1892, the McBride Remnant Valley was s t i l l covered by about 600 meters of glacial ice which did not become sepa rated from the Muir G lacier u n til 1937. By the early 1900's, there was s t i l l about 300 meters of ice over the McBride Remnant Valley and by 1929, this had been reduced to about 200 meters. In 1935 the ice had wasted to about 150 meters. In the early 1950*s, the ice was in the order of 30 to 60 meters thick. When first seen by the author, only a few small blocks of ice, 15 meters thick, were left in the McBride Remnant Valley. In 1948, there was about 7.5 sq km of ice l e f t in the McBride Remnant V alley, but by 1963 th is had been reduced to 1 sq km. The average rate of downwasting in this area has been in the order of 6,4 meters per year. 179 Figure 89. Muir Remnant Glacier around which small ephemeral ponds have developed. Minnesota Ridge flanks the ice on the right (south), with tongues of avalanche debris extending out onto the ice a t (a ) and (B). 180 From the orientation of crag-and-tail features it is suggested that after separation from the Muir Glacier, the residual McBride Remnant ice reversed i t s d ire c tio n of flow north of "The Nunatak". A succession of large glacial meltwater channels, now abandoned, can be traced northward from Goose Cove Creek to Van Horn Creek. A series of much smaller abandoned ice marginal channels can be seen southwest of "The Nunatak" showing the wastage of ice eastward away from th is knob. The p rin cip al stream in th is area today is McBride Remnant Creek which empties into Nunatak Cove. Several small eskers are scattered throughout the McBride Rem nant Valley. The largest of these is still ice cored. Karnes composed of thin-bedded well-sorted sand are particularly well developed in the n o rth -cen tral and southeastern p a rt of the McBride Remnant Valley. Several of these were s t i l l ice cored in 1964. Numerous lin ea r t i l l ridges cross the McBride Remnant Valley and appear to have been developed by the squeezing of water-saturated till into fractures and voids within the ice when it was only a few meters thick. Other ridges developed from till-filled shear planes (flow planes) or from ablation moraine that slid between and around small ice blocks. APPENDIXES 181 APPENDIX I. PEBBLE COUNT LITHOLOGIES Approximately 100 pebble counts were made in till and gravel units in the Upper Muir Inlet area during the summers of 1963-1964. A condensed summary of these is given in Table 4. Table 7 lists the lithology of pebble counts in each strati graphie unit and includes location, together with the percentage of each rock type. As seen in Table 7, the lithologie percentages show v a ria tio n s even w ithin the same formation or member. There are also regional changes in the lithology of the stratigraphie units which are, in part, the result of distance from source area, dilution by tributary streams, and differential resistance to chemical decomposition and mechanical disintegration. This shows particularly in the carbonates versus the igneous rocks. Certainly some of the variability in the lithologie changes is the human error. One of the most common rock types encountered in pebble counts in this part of the National Monument are the igneous plutonics whose compositions range widely as revealed by field study by D. A, Brew (1967) and D. L. Rossman (1963). These rocks include granite, syenite, quartz-diorite, quartz-monzonite, granodiorite, and diorite. It is almost impossible to differentiate all these types clearly in the field. Biotite-hornblende diorite was the most common and stands out in bold contrast in the tills and gravels because of its light color. A pluton 182 TABLE 7 PEBBLE COUNTS OF THE MUIR INLET AREA® Percentage of Rock Types d e Plutonic Location Dike Rocks^ Limestone*' Metasediments Amphibolite Igneous Other Muir T ill North Creek 24 25 21 30 Two-Till Creek 23 25 20 32 Two-Till Creek 21 21 32 26 Upper Forest Creek 35 3 22 39 Upper Forest Creek 24 0 20 56 Orange Creek, 500 m 20 38 22 20 south of Canyon Creek Glacier Bay Till So. side Nunatak Cove 18 25 26 1 30 So. side Nunatak Cove 40 20 21 19 So. side Goose Cove 31 17 27 25 No. side Forest Creek 40 18 27 6 9 No. side Forest Creek 25 21 34 2 18 Upper Forest Creek 27 17 19 37 SW side Casement Glacier 50 7 25 3 15 Station 19A 46 11 15 2 26 Base Station 19A 46 16 14 2 22 Larsen Creek 32 27 26 15 North Creek 25 5 7 2 61 Two-Till Creek 46 20 15 19 Canyon Creek 26 17 28 3 26 00 Van Horn Creek 21 22 32 25 OJ TABLE 7. (Continued) Percentage of Rock Types Plutonic Location Dike Rocks Limestone Metasediments Amphibolite Igneous Other So. side Van Horn Ridge 30 29 14 27 SW part McBride Remnant 23 26 24 27 Valley East of the Nunatak 24 22 20 4 30 East of the Nunatak 25 28 18 1 28 NE of the Nunatak 20 33 13 14 NE of the Nunatak 24 36 20 20 East of the Nunatak 24 30 26 20 East of the Nunatak 23 42 18 17 East of the Nunatak 10 27 19 44 East of the Nunatak 25 25 18 32 East of the Nunatak 32 27 17 2 22 South of the Nunatak 29 23 23 25 No. Fork Muir Remnant R. 29 33 24 14 Orange Creek 25 34 16 ■ 25 Crevasse filling ridge 16 29 20 3 32 east of the Nunatak Interfluve between Lar 24 30 26 20 sen and Whitelaw Crks. H ill 421 37 12 23 8 20 Head of McBride Remnant 27 26 25 3 19 fan Lower Van Horn Gravel Member South side Nunatak Cove 24 17 40 19 South side Nunatak Cove 36 32 11 21 South side Nunatak Cove 29 13 30 28 South side Nunatak Cove 27 14 23 36 00 No, side Goose Cove Del, 37 5 27 31 TABLE 7, (Continued) Percentage of Rock Types Plutonic Location Dike Rocks Limestone Metasediments Amphibolite Igneous Other No. side Goose Cove Cr, 27 13 28 32 above delta Head of Nunatak Cove 32 30 10 4 24 Canyon Creek 25 29 18 1 25 Canyon Creek 30 25 17 2 26 Head alluvial fan 34 25 21 20 McBride Remnant Creek North Creek 16 29 27 28 Orange Creek 25 21 32 22 No. of Westdahl H ills 25 20 28 27 Upper Van Horn Gravel Member No. Fork Muir Remnant R. 24 29 24 23 Head of Nunatak Cove 24 27 27 22 No. side Nunatak Cove 20 38 18 24 So. side Nunatak Cove 36 12 25 27 Head of Goose Cove 36 7 9 48 So. side Goose Cove del. 42 5 6 47 No. side Forest, Cr. at 42 7 12 7 32 mouth of delta No. side Forest Cr. at 28 14 27 9 22 mouth of delta Fault Creek 25 17 38 2 18 So. side Forest Cr. near 30 25 18 2 25 apex of delta So. side Forest Cr. near 33 23 19 3 22 apex of delta Head of Nunatak Cove 35 19 20 1 25 00 TABLE 7. (Continued) Percentage of Rock Types Plutonic Location Dike Rocks Limestone Metasediments Amphibolite Igneous Other Head of Sun Valley Creek 26 30 11 2 31 North Creek 40 21 15 3 21 No. side Canyon Creek 28 29 22 21 So. side Canyon Creek 22 36 15 17 So. side Canyon Creek 33 21 25 1 20 So. side Van Horn Creek 20 34 20 3 23 Head alluvial fan 24 15 34 27 McBride Remnant Creek 1 km so, of so. side of 21 31 24 2 22 Nunatak Cove No. side McBride Valley 13 34 27 26 Glacier Orange Creek 16 32 18 1 33 Wachusett Point 41 9 14 36 No. side Minnesota Ridge 24 35 23 18 apex Stump Cove delta First creek south of 29 18 12 41 Forest Creek 3 km no. of Klotz Hills 27 14 14 45 So. side Wachusett Inlet 38 9 13 40 5 km from mouth Camp Creek, Wachusett 30 13 8 49 Inlet Ablation Till Head Sun Valley Creek 39 21 17 2 21 So. side Van Horn Ridge 44 6 19 31 00 So. side Van Horn Ridge 37 4 14 45 o TABLE 7, (Continued) Percentage of Rock Types Plutonic Location Dike Rocks Limestone Metasediments Amphibolite Igneous Other So. la te ra l moraine 32 16 19 31 McBride Valley Glacier Medial moraine McBride 34 30 22 13 Valley Glacier No. lateral moraine 33 15 13 39 McBride Valley Glacier McBride Remnant ice block 20 35 8 22 Schist-15 McBride Remnant ice block 14 36 16 20 Schist- 1 Greenstone - 13 Relict medial moraine 36 17 20 27 west McBride ice block West end Red Mt, cirque 0 17 0 Volcanic breccia - 80 Greenstone - 2 Gneiss- 1 Terminus Plateau Glacier 34 10 50 south end Seal River Outwash Third creek south of 32 15 11 42 Forest Creek Larsen Creek allu v ial fan 31 27 19 23 Mouth of Coleman Creek 33 18 20 29 Middle of McBride 29 20 10 38 Greenstone-2 00 Remnant Valley Gneiss 1 -vj TABLE 7. (Continued) Percentage of Rock Types Red Green Porphyritic Porphyritic Finegrained Volcanic Volcanic Green Fossiliferous Plutonic Location Breccia Breccia Volcanics Limestone Metasediments Igneous So. side Red Mt. Creek 8 4 41 16 25 6 alluvial fan Middle Red Mt, Creek 0 9 30 23 30 8 alluvial fan No. side Red Mt. Creek 5 12 34 14 25 10 alluvial fan So. side Middle Creek 6 17 39 9 24 5 alluvial fan Middle of Middle Creek 8 19 30 16 17 10 alluvial fan No. side Middle Creek 10 19 35 17 11 8 alluvial fan Middle Creek, 2 km north 2 26 29 8 19 16 East side of Coleman .0 22 21 25 14 16 Creek alluvial fan West side of Coleman 0 23 21 20 19 17 Creek alluvial fan Number of pebbles counted was always 100; for location see Figure 6. ^Range in composition from basalt to andésite, 'Includes some limey shales and sands and conglomerates. ^Meta-silt and claystones, 'Contact phase of diorite, 00 00 ^Includes d iorite, granite, syenite, quartz diorite, quartz monzonite. 189 of batholithic proportions extends across the Upper Muir Inlet area, and probably contributed markedly to the diorite pebbles, cobbles, and boulders in the tills and gravels. Basaltic to andesitic dike rocks constitute a high percentage of the pebbles in many of the counts, and are usually distinguished by their porphyritic texture and contrasting green, gray, and black colors. Local source areas for pebbles of this lithology are at White Thunder Ridge, "The Nunatak", Van Horn Ridge, and Mount Brock (Fig. lO). Perhaps the easiest lithology to recognize as pebbles are the detrital clastic rocks which were originally graywacke, shale, silt- stone, claystone, and conglomerate. These have been metamorphosed to hornfels or argillite and are included here under the heading, meta sediments. Pebbles of this lithology are commonly thin bedded and of highly contrasting colors. Their characteristic hardness, due to high silica content, is also important in identification. They are chert- and flint-like and are, therefore, extremely resistant and commonly constitute as much as 20 to 30 percent of the pebbles in many counts. Their presence in the stratigraphie units actually does not aid in the delineation of any specific source area, as the immediate Upper Muir Inlet region is surrounded by rocks of this lithology (Fig. lO). Carbonate rocks in pebble counts come from a variety of sources, most of which are limestone or limy shale. The percentage of limestone pebbles increases near local outcrops such as around the flanks of the Black Cap Limestone, east of "The Nunatak". The limestone is locally marblized, and contains abundant fossils. Pebbles of this lithology could have been transported into Upper Muir In le t from outcrops known 190 to occur at the head of Riggs, McBride, and Casement Glaciers, but most are undoubtedly of more local o rig in . Volcanic rocks do not constitute a high percentage of the lithology of the pebble counts, except near the eastern margin of the McBride Remnant Valley where greenstone and volcanic breccia fragments are relatively abundant. Sparse pebbles and cobbles of green-weathering phyllitic greenstones occur in the ablation till and outwash. Green schist to green phyllite characterizes a relict medial moraine on the east side of McBride Remnant Valley. Their o rig in a l source was probably the volcanic complex which constitutes the Black Mountain-Sitth-gha-ee Peak area. Near the western base of Middle Mountain, volcanic breccia pebbles c o n stitu te from 40 to 60 percent of the pebble count, demon strating the close proximity of the source area. All of the alluvial fans that are building westward from Coleman Creek to Red Mountain Creek contain a high percentage of volcanic rocks. Although the contrasts are rather subtle, one can see variations in the lithology of the pebble counts. A case in point is the increase in the percentage of diorite pebbles toward the base of the Idaho Ridge Batholith. Here the diorite percentage is as much as 50 percent, whereas in many spots across the McBride Remnant Valley diorite pebbles constitute only 15 to 30 percent of the total count. 191 Generally speaking, counting pebbles was not found to markedly delimit source areas, but used with other parameters it was a definite aid. The close similarity of the lithology of the Glacier Bay Forma tion with that of the upper member of the Van Horn Formation indicates that the source for much of the material of this upper till was the gravel over which Late Neoglacial ice moved. APPENDIX I I. METEOROLOGICAL DATA Meteorological observations were recorded at Nunatak Cove,at the southwest corner of "The Nunatak” (Fig. 6), from June 23 to August 29, 1963, and again from June 19 to September 12, 1964. These records include the maximum and minimum temperatures, temperature range, and mean tem perature, together with the amount of ra in fa ll and overcast. These data are compiled in Table 8. Figure 90 is a graphic plot of the daily maximum and minimum temperatures at Bartlett Cove during the summers of 1963 and 1964, Figure 91 is a sim ilar diagram showing the amount of rainfall over the same period. The Nunatak Cove meteorologi cal site is approximately 60 km north of Bartlett Cove and Gustavus. Table 9 is a compilation of the raw data of maximum and minimum temperatures, rainfall, and amount of overcast at Bartlett Cove during the summer of 1963-1964. Table 10 is a compilation of the 10-year record of mean d aily maximum and minimum tem peratures and monthly totals and averages of precipitation for the Gustavus station. Based on long-term records at Gustavus, rainfall in July of 1963 at Nunatak Cove may have been about normal, whereas rainfall during July, 1964, seems to have been higher than normal. Compared to Gustavus figures, August of 1963 at Nunatak Cove was very dry, whereas August of 1964 seems to have been wetter than normal. The marked con trast in total rainfall at Bartlett Cove during the months of September, 1963 and 1964, is worthy of note, as is the contrast in rainfall between 192 193 TABLE 8 METEOROLOGICAL DATA AT NUNATAK COVE Temperatures* C R a in fa ll, Overcast, Date Max. Min. Range Mean cm s tenths June, 1963 23 10 7 3 8 1.7 10 24 16 6 10 11 0.7 10 25 15 5 10 10 0.1 8 26 16 6 10 11 — — 10 27 15 6 9 10 0.6 10 28 11 5 6 8 0.2 10 29 16 5 11 11 - - 2 30 20 5 15 12 ---- clear Ju ly , 1963 1 19 7 18 13 5 2 12 7 5 10 — 10 3 11 6 5 8 1.1 10 4 20 6 14 13 — — clear 5 22 6 16 14 0.1 5 6 12 7 5 10 — — 10 7 19 5 14 12 — — 5 8 19 5 14 12 — — clear 9 21 5 16 13 — — clear 10 16 8 8 12 0.2 10 11 12 7 5 10 trace 10 12 16 6 10 11 — — 10 13 18 6 12 12 . — — 7 14 18 8 10 13 — — 10 15 15 8 7 11 trace 10 16 12 7 5 10 0.4 10 17 13 8 5 11 1.0 10 18 18 7 11 12 1.4 10 19 16 6 10 11 tra ce 10 20 12 4 8 7 1.6 10 21 13 4 9 9 — — 10 22 18 4 14 11 — — clear 23 11 5 6 8 0.1 10 24 10 6 4 8 0.9 10 25 15 5 10 10 0.6 10 26 17 6 11 12 0.02 10 27 14 5 9 10 10 28 16 6 10 11 0.15 10 194 TABLE 8. (Continued) Temperatures, C R a in fa ll, O vercast, Date Max. Min. Range Mean cms ten th s 29 18 5 13 12 clear 30 15 7 8 11 0.1 10 31 16 5 11 10 trace 10 August , 1963 1 11 5 6 8 0.6 10 2 17 5 12 11 0.25 10 3 11 6 5 8 0.4 10 4 16 6 10 11 1.1 10 5 10 6 4 8 0.65 10 6 12 6 6 9 0.5 10 7 13 6 7 10 0.45 10 8 12 5 7 8 1.7 10 9 16 4 12 10 — — clear 10 18 3 15 10 — — clear 11 22 5 17 13 * - clear 12 22 6 16 14 — - clear 13 21 7 14 14 — — clear 14 18 8 10 13 * - 5 15 15 7 8 11 — - 10 16 16 7 9 11 --- 10 17 18 6 12 12 — — 5 18 13 7 6 10 - - 10 19 14 5 9 10 -- 8 20 13 4 9 8 — - 5 21 17 4 13 10 - — 1 22 16 2 14 10 — — 6 23 18 3 15 10 — — 1 24 19 4 15 11 — — clear 25 19 5 14 12 ------clear 26 15 6 9 10 0.5 10 27 19 5 14 12 — — clear 28 18 4 14 11 - — clear 29 18 4 14 11 — — clear June, 1964 19 15 5 10 10 0.2 10 20 15 5 10 10 trace 10 21 11 6 5 8 0,5 10 22 16 4 12 10 — — 2 23 18 2 16 10 — — clear 24 15 6 9 10 0,2 10 25 10 5 5 7 0.9 10 26 10 5 5 7 0.05 10 27 16 5 11 10 — — clear 195 TABLE 8, (Continued) Temperatures, C R a in fa ll, O vercast, Date Max. Min. Range Mean cms tenths 28 13 5 8 9 trace 10 29 10 5 5 7 0.6 10 30 10 4 6 7 0.24 10 Ju ly , 1964 1 12 5 7 8 0.7 10 2 11 4 7 7 1.3 10 3 10 6 4 8 2.0 10 4 15 6 9 10 1.1 10 5 10 5 5 7 0.6 10 6 16 4 12 10 — — clear 7 16 7 9 12 0.04 10 8 17 6 11 11 — — clear 9 13 5 8 6 0.4 10 10 12 5 7 8 1.3 10 11 10 5 5 7 1.5 10 12 12 5 7 8 0.6 10 13 18 5 13 11 — — clear 14 22 6 16 14 — — clear 15 21 6 15 13 —— clear 16 20 7 13 13 — — clear 17 18 6 12 12 — — 10 18 12 6 6 8 — — 10 19 11 5 6 8 0.3 10 20 20 5 15 12 --- clear 21 20 6 14 13 — — clear 22 13 7 6 10 0.1 10 23 12 7 5 12 1.7 10 24 10 6 4 8 0.8 10 25 11 5 6 8 0.8 10 26 16 4 12 10 — — clear 27 10 6 4 8 2.4 10 28 11 7 4 8 3.8 10 29 15 6 9 10 0.1 10 30 15 6 9 10 - 10 31 16 6 10 11 1.8 10 August, 1964 1 13 6 7 9 — — 10 2 13 5 8 9 0.2 10 3 18 5 13 11 — — 10 4 16 6 10 11 — — 10 5 15 6 9 10 — — 10 6 18 5 13 11 ------5 7 18 5 13 11 ------clear 196 TABLE 8. (Continued) Temperatures, C R a in fa ll, O vercast, Date Max. Min, Range Mean cms tenths 8 16 6 10 11 0.1 10 9 16 6 10 11 — — clear 10 12 5 7 8 1.1 10 11 19 6 13 12 — — clear 12 13 7 6 10 1.0 10 13 11 5 6 8 0.5 10 14 11 5 6 7 0.5 10 15 10 5 5 7 1.4 10 16 12 5 7 8 0.3 10 17 16 5 11 10 — — 10 18 10 5 5 7 0.8 10 19 10 5 5 7 0.02 10 20 12 5 7 8 1.0 10 21 13 5 8 9 2.0 10 22 15 4 11 9 --- 10 23 9 4 5 6 0.6 10 24 9 5 4 7 2.1 10 25 20 5 15 12 — — clear 26 10 7 3 8 1.4 10 27 19 4 15 11 --- 5 28 10 5 5 7 1.4 10 29 16 4 12 10 — — 5 30 14 3 11 8 — — 5 31 10 5 5 7 0.1 10 September, 1964 1 17 4 13 10 — — clear 2 16 2 14 9 --- clear 3 16 2 14 9 — - clear 4 16 4 12 10 ' ---- clear 5 10 3 7 6 — - 10 6 19 3 16 11 — — clear 7 17 6 11 11 --- clear 8 16 0 16 8 — — clear 9 16 1 15 9 — — clear 10 16 1 15 9 — - clear 11 16 1 15 9 — — clear 12 16 5 11 10 trace 5 27 24 » 21 f 18 ,\:V.An W . ■ > ha “ 10 P ^ W W w\%w ^ z 1^7 —-1963 / % : é r f V i W y 2 -l _L _L X X J_ X XX K) 15 20 29 30 5 10 15 20 25 10 15 20 25 15 10 15 20 25 30 JUNE I J U LY T AUGUST SEPTEMBER l Figure 90. Maximum and minimum temperatures at Bartlett Cove for the seasons June-September, 1963-1964. \0 ^4 5 0 ^ 46 s 40 -1963 tï •1964 w 2 35 30 z 25 0 20 i T î 1a. i I II: î<1 15 ( I •. I II '»! 0. 10 A A 5 f 0 I L ± J. _L ± ± ± _L X X X K) * 20 25 34 10 19 20 25 30 K) 19 20 25 6 10 15 20 25 30 J UNE ' J ü LY ' AUGUST SEPTEMBER Figure 91. Rainfall at Bartlett Cove for the seasons June-September, 1963-1964. \0 00 199 TABLE 9 METEOROLOGICAL DATA AT BARTLETT COVE Temperatures, C R a in fa ll, Date Max. Min. Range Mean cms Overcast® Ju n e, 1963 1 18 7 11 12 2.4 MC 2 17 6 11 12 trace MC 3 13 6 7 10 0.8 C 4 12 6 6 9 0.4 C 5 12 7 5 10 0.2 C 6 13 5 8 9 trace MC 7 17 6 11 11 — — MCL 8 18 7 11 13 0.7 MC 9 15 6 9 11 0.1 MC 10 16 7 9 12 — — C 11 14 7 7 11 1.0 c 12 15 8 7 12 0.8 c 13 16 7 9 12 — — MCL 14 16 7 9 12 trace C 15 13 7 6 10 1.1 C 16 14 8 6 11 0.5 C 17 17 10 7 14 — — MCL 18 15 8 7 12 0.2 MC 19 16 7 9 12 trace MC 20 14 7 7 11 trace C 21 16 8 8 12 — — MC 22 14 9 5 12 trace C 23 14 10 4 12 0.5 C 24 13 8 5 11 — — C 25 15 7 8 11 0.3 MC 26 15 8 7 12 — — C 27 14 7 7 11 — — C 28 13 8 5 11 0.8 C 29 20 8 12 14 0.2 MCL 30 23 9 14 16 — — CL Ju ly , 1963 1 19 9 10 14 — — C 2 19 8 11 14 1.0 C 3 16 8 8 12 trace C 4 20 9 11 15 — — CL 5 18 8 10 13 1.6 C 6 19 8 11 14 0.2 C 200 TABLE 9. (Continued) Temperatures, C_____ Rainfall, Date Max. Min. Range Mean cms Overcast 7 18 8 10 13 H » MCL 8 19 8 11 14 — — CL 9 19 9 10 14 CL 10 19 9 10 14 — — MCL 11 17 8 9 13 — — MCL 12 18 9 9 14 0.2 C 13 19 10 9 15 0.5 C 14 18 10 8 14 — — MC 15 19 10 9 15 — - MC 16 19 10 9 15 — - C 17 18 11 7 15 tra ce C 18 15 10 5 13 1,2 c 19 17 9 8 13 3.5 c 20 20 8 12 14 0.8 MC 21 18 7 11 13 - " CL 22 18 7 11 13 trace CL 23 20 6 14 13 — - MC 24 ----- missing ----- — - C 25 20 6 14 13 — — c 26 17 6 11 12 0.3 MC 27 ----- missing ---- — - MCL tf 28 — — — - 29 U — — — — 11 30 — - — — 31 0.8 C August , 1963 1 18 8 10 13 — — MC 2 19 10 9 14 0.4 C 3 — — - m is s in g ------— - C 4 18 11 7 14 ------C 5 13 11 2 12 0.3 C 6 17 11 6 14 0.1 c 7 14 10 4 12 0.5 c 8 15 10 5 13 0.8 c 9 17 6 11 12 trace CL 10 18 6 12 12 —— CL 11 23 6 17 15 — CL 12 13 9 4 11 ------CL 13 — — 10 — — — — ------CL 14 24 — *- — — — — * — MCL 15 16 13 3 15 — — C 16 16 11 5 14 0.1 C 17 17 10 7 14 tra ce MC 18 16 11 5 14 — MC 19 15 9 6 12 — - MC 201 TABLE 9. (Continued) Temperatures, C )ate Max. Min. Range Mean cms Overcast 20 -— missing ---- ^ — — — 21 17 9 8 13 tra ce MCL 22 18 7 11 13 — — MC 23 ----- missing ------CL 24 22 7 15 15 — — CL 25 21 7 14 14 — — CL 26 18 10 8 14 0.2 C 27 ----- missing ---- — — — — 28 18 7 11 13 — — CL 29 20 6 14 13 — — CL 30 22 8 14 15 — — CL 31 22 10 12 16 — - MCL September, 1963 1 16 11 7 14 — — MC 2 — missing —— 0.9 C 3 13 10 3 12 0.5 C 4 13 10 3 12 0.3 C 5 12 9 3 11 2.3 C 6 16 9 7 13 2.2 C 7 16 10 6 13 1.4 C 8 16 — — — — — — 0.5 C 9 — — 9 --- — — 0.2 C 10 13 9 4 11 — — MC 11 13 9 4 11 0.3 C 12 12 9 3 11 2.1 C 13 15 9 6 12 0.2 MC 14 12 9 3 11 0.4 MC 15 9 7 2 8 1.9 C 16 11 7 4 9 0.2 MC 17 12 7 5 10 1.6 C 18 12 11 1 12 4.8 C 19 12 9 3 11 0.6 c 20 12 6 6 9 2.9 c 21 11 8 2 10 1.9 c 22 15 9 6 12 0.1 MC 23 11 6 5 9 0.1 MC 24 9 8 1 9 1.9 c 25 11 7 4 9 1.4 MC 26 12 8 4 10 1.9 C 27 11 8 3 10 - - MCL 28 - — missing ——- — — C 29 13 4 9 9 1.4 C 30 12 7 5 10 1.7 C 202 TABLE 9. (Conti nued) Temperatures, C R a in fa ll, Date Max. Min. Range Mean cms Overcast Ju n e, 1964 1 18 8 10 13 — — — — 2 12 8 4 10 0.13 C 3 14 7 7 11 0.9 MCL 4 15 7 8 11 0.1 C 5 13 8 5 11 0.5 C 6 16 7 9 12 — — MCL 7 18 8 10 13 — — MCL 8 19 7 12 13 --- MC 9 19 6 13 13 —— MC 10 12 9 3 11 -- C 11 14 8 6 11 — — C 12 18 6 12 12 — — CL 13 18 8 10 13 0.2 C 14 16 7 9 13 0.4 MC 15 —- missing -— — — - - 16 II — — - - 17 If - - - - 18 19 7 12 13 - — — — 19 -— missing -— 4.4 C 20 16 8 8 12 — ” “ - 21 16 9 7 13 0.3 MC 22 20 8 12 14 0.2 C 23 18 8 * 10 13 —— MC 24 12 8 4 10 — — MC 25 ------missing ------0.7 C If 26 — - C 27 12 7 5 10 — — C 28 ------missing ------■ ------C 29 16 8 8 12 - — MC 30 11 8 3 10 0.2 C 31 - - - missing - — 0.4 C Ju ly , 1964 1 13 8 5 11 0.1 C 2 ------missing ------— — C fl 3 — — C 4 13 10 3 12 0.4 C 5 - — missing - — 0.7 C 6 16 7 9 12 — — MCL 7 17 9 3 13 0.3 MC 8 - — missing --- “ - - 9 If C 10 II C 203 TABLE 9. (Continued) Temperaturesf C Date Max. Min. Range Mean cms Overcast 11 14 9 5 12 0.9 C 12 12 8 4 10 1.9 C 13 18 8 10 13 * — CL 14 22 8 14 15 — CL 15 22 9 13 16 — — CL 16 21 11 10 16 — — CL 17 - 20 9 11 15 — — MC 18 16 9 7 13 . C 19 18 9 9 14 — MC 20 20 7 13 14 — — MCL 21 20 8 12 14 — — CL 22 18 11 7 15 0.5 C 23 13 9 4 11 0.6 C 24 13 9 4 11 0.2 C 25 12 6 6 9 0.8 C 26 19 8 8 14 0.1 MC 27 ----mi ssing ----- — — --- 28 12 9 3 11 2.3 C 29 17 9 8 13 0.1 MC 30 16 10 6 13 tra ce C 31 14 9 5 12 0.1 C August , 1964 1 — rnissing ---- — — “ - 2 16 9 7 13 — “ C 3 18 10 8 14 — — MC 4 16 7 9 12 — — C 5 16 10 6 13 — - C 6 18 10 8 14 --- MC 7 18 8 10 13 MCL 8 17 9 8 13 0.2 MC 9 15 8 7 12 - — MC 10 12 9 3 11 0.9 C 11 ——— mi ssing ---- — — MC 12 19 10 9 15 1.3 C 13 15 10 5 13 0.3 C 14 12 8 4 10 2.1 C 15 10 8 2 9 1 .1 C 16 12 8 4 10 0.4 C 17 16 8 8 12 0.7 C 18 14 8 6 11 0.3 c 19 13 9 4 11 0.7 c 20 18 9 9 14 0.5 MC 21 15 9 6 12 0.4 MC 22 16 7 9 12 tra ce MCL 23 —- — mi ssing ---- tra ce C 204 TABLE 9. (Continued) Temperatures, C R a in fa ll, Date Max. Min. Range Mean cms Overcast 24 13 8 5 11 2.6 C 25 16 8 8 12 0 .4 MCL 26 16 9 7 13 0 .9 C 27 18 6 12 12 — — MC 28 12 8 4 10 0.1 C 29 17 8 9 13 0.9 CL 30 15 5 10 10 — — MC 31 13 8 5 0 .4 C September , 1964 1 15 8 7 12 0.1 MCL 2 16 4 12 10 — — C 3 18 3 15 11 — — MCL 4 14 7 7 11 ---- MCL 5 17 6 11 12 — — C 6 16 7 9 12 — — MCL 7 17 7 10 12 — — C 8 17 3 14 10 — — CL 9 16 4 12 10 ---- CL 10 16 4 12 10 - - CL 11 16 4 14 10 — — CL 12 16 5 11 11 — — C 13 12 8 4 10 0.9 c 14 13 8 5 11 0 .6 c 15 12 8 4 10 0.21 c 16 13 7 6 10 0.6 c 17 12 6 6 9 0.1 c 18 10 7 3 9 0 .8 c 19 10 7 3 9 0.14 c 20 12 8 4 10 0 .2 c 21 12 7 5 10 0.2 c 22 12 8 4 10 0.3 c 23 10 7 3 9 0.6 c 24 10 5 5 8 0.2 MCL 25 9 3 6 6 — — MC 26 11 5 6 8 0.5 c 27 11 7 4 9 0.2 c 28 10 4 6 7 0.1 c 29 8 6 2 7 0.1 c 30 9 4 5 7 0 .3 c ®CL, clear; MCL, mostly cloudy; MC, mostly clear; and C, cloudy. TABLE 10 METEOROLOGICAL DATA FOR GUSTAVUS, ALASKA, 1951-1960 Year Jan Feb Max Apr May June July Aug Sept Oct Nov Dec Annual Average P recip itatio n, cm 1951 4.7 3.5 3.5 7.6 6.3 4.4 6.0 9.6 14.5 10.3 15.6 7.6 99 1952 14.9 5.5 9.5 8.9 9.9 4.5 3.2 8.0 28.2 39.5 16.4 10.5 160 1953 ■ 5.7 18.0 6.8 4.1 6.7 5.3 8.3 12.6 13.2 32.2 9.6 16.7 140 1954 8.9 14.2 5.3 3.4 7.7 3.7 7.6 2.5 13.6 20.4 18.2 17.7 124 1955 13.3 7.6 12.1 2.4 6.5 8.3 4.2 13.3 16.1 17.5 7.7 4.0 113 1956 4.5 9.5 5.8 3.2 9.5 8.0 7.7 24.0 14.9 14.3 33.1 26.6 163 1957 3.9 11.6 1.6 4,7 7.5 2.4 7.5 4.8 17.4 12.6 20.5 14.2 109 1958 12.0 4.2 2.0 4.2 6.2 5.2 15.4 13.2 11.9 30.0 14.0 17.1 135 1959 5.0 8.3 1.1 7.2 6.5 2.0 12.4 12.7 10.9 17.0 21.0 16.5 130 1960 7.5 6.4 7.7 5.2 4.6 8.0 11.0 10.3 20.0 22.7 11.4 19.4 135 Average 8.0 8.8 7.1 5.0 7.2 5.2 8.3 11.0 16.1 21.6 16.9 15.1 130 Mean Daily Maximum and Minimum Temperature, C Daily -1.0 1.6 3.3 8.0 12.2 15.4 17.2 16.6 14.0 8.4 4.1 1.6 8.4 Max Daily -8.1 -5.5 -4.4 -0.5 2.8 6.6 9.0 8.8 5.5 2.2 -1.1 -4.4 1 Min lO o 206 Nunatak Cove and Bartlett Cove for the month of July, 1964. Rain fre quently falls in Upper Muir Inlet when none is reported at Bartlett Cove. As is perhaps obvious, temperatures at Nunatak Cove are lower than those at Bartlett Cove and Gustavus, at least during the summer months. There is perhaps a sheltering effect at Nunatak Cove due to its position in the lee of "The Nunatak". To the author's knowledge, the annual and decade trend of m eteorological data at B a rtle tt Cove has not been analyzed and compared with similar long-term records at Gustavus and Cape Spencer, which are, respectively, to the east and west. It is not the purpose to do so here, yet the contrasts between these stations might be interesting, especially any micrometeorological discrepancies between Gustavus and B a rtle tt Cove. APPENDIX I I I . MECHANICAL ANALYSES AND CUMULATIVE CURVES OF LAKE SILTS, TILLS, AND GRAVELS Cumulative Curves M-1 through M-6 (Fig, 92) are the grain size distribution plots of lacustrine sediments in Upper Muir Inlet taken from the middle member of the Van Horn Formation. Curve M-2, which shows the best sorting, is a surface sample from the topset beds of Nunatak Cove Delta. It is interesting to note that the fine deltaic sediments now forming in the brackish water of Muir Inlet have much in common with the lake sediments within the Van Horn Formation. Marine varve-like sediments are probably forming at the bottom of Muir Inlet now, and future oceanographic work here will help to demonstrate or disprove this point. Table 11 gives the mechanical composition of these sediments. Cumulative Curves 63-1 through 63-31 (Figs. 93-99) are grain size distribution plots of the Muir Formation, Glacier Bay Formation, and the Van Horn gravel. Table 12 id e n tifie s each of these curves. Note the similarity of the curves of the Glacier Bay Formation and the general lack of sorting. 207 FIGURE 92.CRAIM SIZE DISTRIBUTION DIAGRAM , LACUSTRINE SILTS 100 00 00 7 0 5 0 3 0 0 5 0 . 2 5 0 . 0 5 0.001 0.0005 0.0002. FINE pEAYFWe MEDIUM OWAVEL SOT CLAY 5AM0 TABLE 11 MECHANICAL COMPOSITION OF LACUSTRINE SILTS® Particle Size Distribution, percent Very Very Medium Fine Fine Sam Coarse Coarse Sand, Sand, Sand, S ilt, Fine ple Sand, Sand, 0.5- 0.25- 0.1- Total 0.05- Clay, Clay, Textural No. Location 2-1 mm 1-0.5mm 0.25mm 0.1mm 0.05mm Sands 0.002mm <0.002mm < 0.0002mm Class M-1 North Creek 0.7 1.7 2.3 9.6 20.7 35 58.6 6.4 0.8 S ilt loam M-2 Nunatak Cove 0.0 0.0 0.1 7.9 46.9 54.9 41.8 3.3 1.3 Sandy loam M-3 Sun Creek 0.0 0.3 0.2 0.2 0.2 0.9 77.2 21.9 2.9 S ilt loam M-4 Two-Till Creek 0.0 0.0 0.0 0.3 4.8 5.1 92.0 2.9 1.0 S ilt M-5 Westdahl H ills, 0.0 0.1 0.0 0.1 0.2 0.4 80.4 19.2 2.6 S ilt west side loam M-6 Canyon Creek 0.0 0.1 0.1 0.5 0.3 1.0 83.9 15.1 2.2 S ilt loam See Figure 6 for location, fO o '£) FIGURE 93. GRAIN SIZE DISTRIBUTION DIAGRAM 100 00 6 0 7 0 5 0 a 4 0 3 0 0 2 5 0.1 0 .0 5 ooi 0.005 6.002 a 001 0.0005 o*oooa C0AA3C MEDIUM FINE IVEHTfFiNfi ND MEDIUM 0 RAVEL CLAY SAMD SAND JAND O FIGURE 94. CRAIN SIZE DISTRIBUTION DIAGRAM t o o «0 60 70 50 2 40 30 20 0.1 0.05 001 0005 0 . 0 0 7 . a 001 0-0005 0.0002 COARSE MEDIUM OAAVEL AANO FIGURE 95. CRAIN SIZE DISTRIBUTION DIAGRAM 100 90 7 0 ■ ^ * I - 50 30 20 0 l5 &Z5 0.05 a c t 0.005 0.002. 0.001 0.0005 0 '0 6 0 % h-•ro MEDIUM ORAUCL SUT CLAY 6RAVCL ro FIGURE 96 CRAIN SIZE DISTRIBUTION DIAGRAM 100 00 70 50 2 40 30 20 OS 0.1 0.05 a c t 0.005 0 0 0 2 a 001 0.0005 ^ O ’ o o o ^ MEDIUM MEDIUM O ttW C L CLAY SAMD W FIGURE 97. grain SIZE DISTRIBUTION DIAGRAM t o o 90 00 /■' 'L 70 5 0 30 20 Ol5 0.05 0.005 0.002 0001 0.0005 O'0002. MEDIUM SILT CLAY lO MEDIUM 0 RAVEL SA MO FIGURE 98. GRAIN SiZE 0l3TRl8UTt0N DIAGRAM 100 9 0 00 7 0 6 0 5 0 - r 3 0 20 Û 5 0.1 0 .0 5 Ol005 0.002 &00I aooo5 M FINE CLAY MËOlUM » * A V (L JAND SILT FIGURE 99. GRAiM SIZE DISTRIBUTION DIAGRAM 100 «0 SO 70 SO => 40 30 03 0.05 001 O.OOZ 0,001 0.0005 0.0000- Fine coaw c medwm FINE |V£RTfFi« MEDIUM GRAVEL SILT gRAVCL I 3 AND SAMP jAWO JAND O' TABLE 12 MECHANICAL COMPOSITION OF TILLS AND GRAVEL* Particle Size Distribution, percent Very Very Medium Fine Fine Sam Coarse Coarse Sand, Sand, Sand, S ilt, ple Sand, Sand, 0.5- 0.25- 0.1- Total 0.05- Clay, Forma Textural No. Location 2-1 mm 1-0.5mm 0.25mm 0 .1mm 0.05mm Sands 0.002mm < 0 .002mm tion Class 63-1 Head of Goose 29.4 21.1 7.4 9.6 4.7 72.3 18.8 8.9 LVH Sandy clay Cove loam 63-2 Whitelaw Creek 20.1 21.4 1.6 7.7 5.8 56.6 32.7 10.7 GET Sandy loam 63-3 Head of Larsen 14.3 14.0 4.7 11.8 7.3 52.1 35.5 12.4 GET Sandy clay Creek loam 63-4 Crevasse fil 12.8 11.5 7.0 12.8 8.5 52.6 35.6 11.8 GET Loam ling ridge 63-5 North Creek 8.7 13.4 4.6 17.8 13.8 58.3 37.4 4.3 MT Sandy loam 63-6 Westdahl H ills 16.2 15.6 8.5 15.8 7.0 63.1 28.6 8.3 GET Sandy loam 63-7 Two-Till Creek 6.9 9.0 4.9 12.4 10.8 44.0 41.8 14.2 GET Loam 63-8 Two-Till Creek 13.0 19.9 5.6 13.9 8.2 60.6 36.5 2.9 MT Sandy loam 63-9 Sun Creek 21.9 18.9 3.1 9.2 5.4 58.5 31.9 9.6 GET Sandy loam 63-10 N. Station 19A 9.0 11.6 7.6 13.5 8.3 50.0 36.8 13.2 GET Loam 63-11 NW of Forest 12.6 16.5 4.4 13.7 8.9 56.1 36.1 7.8 GET Sandy loam Creek 63-12 No. of Forest 13.0 11.8 7.1 13.0 8.6 53.5 35.5 11.0 GET Sandy loam Creek 63-13 Larsen Creek 7,0 10.1 7.1 13.2 10.4 47.8 39.6 12.6 GET Loam ( lower) 63-14 Whitelaw Creek 9.4 15.3 2.6 10.0 7.0 44.3 39.5 16.2 GET Loam (lower) 63-15 Coleman Creek 15.1 10.5 6.3 13.1 11.2 56.2 39.1 4.7 GET Sandy loam (mouth) TABLE 12, (Continued) Particle Size Distribution, percent Very Very Medium Fine Fine Sam Coarse Coarse Sand, Sand, Sand, S ilt, ple Sand, Sand, 0.5- 0.25- 0.1- Total 0.05- Clay, Forma Textural No. Location 2-1 mm 1-0,5mm 0.25mm 0 .1mm 0.05mm Sands 0.002mm < 0.002mm tion Class 63-16 Goose Creek 15.2 19.6 3.8 11.6 7.1 57,3 33,8 8.9 GBT Sandy loam 63-17 McBride Rem 13,9 15.7 4.3 11.8 7.8 53.5 34.5 12.0 GBT Sandy loam nant Creek 63-18 Canyon Creek 18.6 14.9 4.7 11.2 7.5 56.9 33.2 9.9 GBT Sandy loam 63-19 South Canyon 16.1 17.0 4.6 12.7 8.0 58.4 34.9 6.7 GBT Sandy loam Creek 63-20 Van Horn Creek 10.3 14.0 3.6 10.9 8.9 47.7 44.8 7,5 GBT Sandy loam 63-21 McBride Rem 12.6 18.1 4.3 12.3 7.8 55.1 37.3 7.6 GBT Sandy loam nant Creek 63-22 Hill 421 9.7 11.2 7.2 13.0 8.0 49.1 38.0 12.9 GBT Loam 63-23 No, of Forest 10.2 11.6 6.7 13.0 8.9 50.4 43.9 5.7 GBT Sandy loam Creek 63-24 Muir Remnant R. 12.1 13.3 9.8 18.7 11.6 65.5 31.8 2.7 GBT Sandy loam (no. fork) 63-25 Casement Glac. 13.8 20.0 3.4 16.7 11.9 65.8 28.9 5.3 MT Sandy loam west side 63-26 N, of McBride 9.4 18.3 5.4 16,8 10.1 60.0 33,4 6.6 GBT Sandy loam Glacier 63-27 Casement Glac. 15.6 11.7 6.6 12,1 7,4 53,4 33.7 12.9 GBT Sandy loam west side 63-28 Orange Creek 9.9 14.7 2.6 13.2 9.8 50.2 40.1 9.7 GBT Loam 63-29 Nunatak Cove 15.4 17.4 3.8 14.9 10.4 61,9 31.6 6.5 GBT Sandy loam !-•to 00 TABLE 12. (Continued) P article Size Distribution, percent Very Very Medium Fine Fine Sam Coarse Coarse Sand, Sand, Sand, S ilt, ple Sand, Sand, 0,5- 0.25- 0 .1- Total 0.05- Clay, Forma Textural No. Location 2-1 mm 1-0 .5mm 0.25mm 0 .1mm 0.05mm Sands 0 .002mm < 0 .002mm tion Class 63-30 Casement Glac. 11.4 14.0 10.1 19.0 11.8 66.3 23.0 12.3 MT Sandy loam west side 63-31 Orange Creek 9.5 13.2 10.0 18.8 13.6 65.1 28.2 8.3 MT Sandy loam ®See Figure 6 for location. '^LVH, Lower Van Horn gravel; MT, Mulr T ill; GBT, Glacier Bay T ill. ND \Û BIBLIOGRAPHY Ahlmann, H. W,, 1948, Glaclological Research on the North Atlantic C oasts, Roy. Geog. Res. Ser. no. 1, London, 83 p. Aitken, J. D. , 1959, Atlin Map Area, British Columbia, Canadian Geol. Survey, Mem. 307, pp 1-89. Andrews, C. L., 1903, Muir Glacier, Natl. Geog. Mag., vol. 14, pp 441- 444. Andrews, J. T., and Smithson, B. B,, 1966, Till Fabrics of the Cross Valley Moraines of North-Central Baffin Island, Northwest Territories, Canada, Geol. Soc. America Bull., vol. 77, pp 271- 2 9 0 . Arnborg, L. , 1955, Ice-Marginal Lakes at Hof fellsjb'kull, Geograf. Ann,, vol. 37, pp 202-228. Arnow, S . , 1959, Drumlins and Related Streamline Features in the Warwick- Tokio Area, North Dakota, Am. Jour. Sci., vol. 257, pp 191-203. Baldwin, S. P., 1893, Recent Changes in Muir Glacier, Amer. Geologist, vol. 11, pp 367-375. Barendsen, G. W., Deevey, E. S., and Gralenski, L. J . , 1957, Yale Natural Radiocarbon Measurements III, Science, vol. 126, pp 908- 919. Bengtson, K, B., 1962, Recent History of the Brady Glacier, Glacier Bay National Monument, Alaska, USA, Symposium of Obergurgl, Inter- natl. Assoc. Scientific Hydrology Pub. no. 58, pp 78-87, Gentbrugge, Belgium. Bergsten, K. E., 1943, The Morphology of Some Glaciofluvial Deposits, Geograf. Ann., vol. 25, pp 116-128. Boundary Atlas of Alaska, Sheets, 14, 15, 17, 18, 1:160,000 (Survey of 1895). Brew, D. A., 1967, unpublished manuscript, U.S. Geol. Sur., Menlo Park, California. Brooks, A. H., 1906, The Geography and Geology of Alaska, U.S. Geol. Survey Prof. Paper 45. 220 221 Buddington, A. F ., 1927, Abandoned Marine Benches in Southeastern Alaska, Am. Jour. Sci., vol. 13, pp 45-52. ______, and Chapin, T., 1929, Geology and Mineral Deposits of Southeastern Alaska, U.S. Geol. Survey Bull. 800. Carol, Hans, 1947, The Formation of Roches Moutonnées, Jour. Glaciology, vol. 1, no. 2, pp 57-59. Cook, J . H ., 1946, Kama Complexes and Perforation Deposits, Am. Jour. Sci., vol. 244, pp 573-583. Cooper, W. S., 1921, The Recent Ecologie H istory of G lacier Bay, Alaska, Ecology, vol. 4, pp 93-127. ______, 1923, The Recent Ecologie H istory of G lacier Bay, Alaska, Ecology, vol. 4, pp 93-123, 223-246, 355-365. , 1924, The B attle of Ice and F orest, American Forest and Forest Life, vol. 30, no. 364, pp 195-198, 234, , 1931, A Third Expedition to G lacier Bay, Alaska, Ecology, vol. 12, pp 61-95. , 1937, The Problem of G lacier Bay, Alaska: A Study of Glacier Variations, Geog. Rev,, vol. 27, no. 1, pp 37-62. , 1939, A Fourth Expedition to G lacier Bay, Alaska, Ecology, vol. 20, pp 130-155. , 1942, Vegetation of the Prince William Sound Region, Alaska: With a Brief Excursion into Post-Pleistocene Climatic H istory, Ecology Monographs, vol. 12, no. 1, pp 1-22. Cushing, H. P., 1891, Notes on the Muir Glacier Region, Am. Geologist, vol. VIII, pp 207-230. ______, 1892, Notes on the Geology of the Vicinity of Muir G lacier, N atl. Geog. Mag., vol. IV, pp 56-62. ______, 1896, Notes on the Areal Geology of Glacier Bay, Trans. N.Y. Acad. S c i., vol. 15, pp 24-34. Davidson, G., 1904, The Glaciers of Alaska that are Shown on Russian Charts or Mentioned in Older Narratives, Geog. Soc. Pacific, Trans, and Proc. series II, vol. 3, pp 1-98. Decker, H. F ., 1966, Soil Development and Ecologie Succession in a De glaciated Area of Muir In le t, Southeast Alaska, Ohio State Univ. Res. Foundation, Inst. Polar Studies, Rept. 20, pp 73-83. 222 Dyson, J. L., 1952, Ice Ridged Moraines and Their Relation to Glaciers, Am. Jour, Sci,, vol. 250, pp 204-211, Elson, J. A., 1957, Origin of Washboard Moraines, Geol. Soc, America Bull., vol. 68, p 1721 (abstract). F airb rid g e, R. W,, 1961, E u static Changes in Sea Level, Physics and Chemistry of the Earth, vol. 4, no. 32, pp 99-185. Field, W, 0,, Jr., 1924-1926, The Fairweather Range: Mountaineering and Glacier Studies, Appalachia, vol. 16, pp 460-472, , 1932, The Glaciers of the Northern Part of Prince William Sound, Alaska, Geogr. Rev,, vol. 22, pp 361-388, ______, 1937, Observations on Alaskan Coastal Glaciers in 1935, Geog, Rev,, vol. 27, pp 63-81, ______, 1942, Glacial Studies in Alaska, Geog. Rev., vol. 32, pp 154-155. , 1947, Glacier Recession in Muir Inlet, Glacier Bay, Alaska, Geog, Rev., vol. 37, pp 369-399, ______, 1964, w ritten and oral communication, ______, 1967, written communication. Flint, R. F., 1928, Eskers and Crevasse Fillings, Am. Jour. Sci,, vol. 15, pp 410-416, , 1966, Comparison of Interglacial Marine Stratigraphy in Virginia, Alaska, and Mediterranean Areas, Am. Jour. Sci., vol. 264, pp 673-684. Gilbert, G. K., 1904, Glaciers and Glaciation, Harriman Alaska Expedi tion, vol. 3, pp 16-39. Goldthwait, R. P., 1963, Dating the Little Ice Age in Glacier Bay, Alaska, Intern. Geol. Cong. XXI, 1960, p t, XXVII, pp 37-46, , McKellar, I, C., and Cronk, C., 1963, Fluctuations of Crillon Glacier System, Southeast Alaska, Intern, Assoc. Sci Hydrology Bull,, vol. 8, pp 62-74. ______, 1965, field notes. , 1966a, Evidence From Alaskan Glaciers of Major Climatic Changes, Royal Met, Soc. Proc, of the Inter, Symp. on World Climate from 8000 to 0 B.C., pp 40-53. 223 Goldthwait, R. P., 1966b, Soil Development and Ecological Succession in a Deglaciated Area of Muir Inlet, Southeast Alaska, Ohio State Univ. Res. Foundation, Inst. Polar Studies, Rept. 20, pp 1-18. Gravenor, C. P., and Bayrock, L. A., 1955, Stream-Trench Systems in East-Central Alberta, Res. Coun, of Alberta, Prelim. Rept 56-4. ______, and Kupsch, W. 0., 1959, Ice Disintegration Features in Western Canada, Jour. Geol., vol. 67, pp 48-64. Hanson, G., 1934, The Bear River Delta, Alaska, and its Significance Regarding Pleistocene and Recent Glaciation, Trans. Royal Soc. Canada, sec. 4, Geol. Sci., 3rd series, vol. 28, pp 179-185. Harrison, P. W,, 1957, A Clay-Till Fabric, its Character and Origin, Jour. Geol., vol. 65, pp 275-308. Haselton, G. M., 1966, Glacial Geology of Muir Inlet, Southeast Alaska, Ohio State Univ., Inst. Polar Studies, Rept. 18, 34 p. Herrick, F. H., 1892, Microscopic Examination of Wood from the Buried Forest, Muir Inlet, Alaska, Supplement III to H. F. Reid's Studies of Muir Inlet, Natl. Geog. Mag., vol. IV, pp 75-77. Hicks, S. D ., and Shofnos, W., 1965, The Determination of Land Emer gence from Sea Level Observations in Southeastern Alaska, Jour. Geophy, R es., vol. 70, pp 3315-3320. Heusser, C. J., 1960, Late Pleistocene Environments of North Pacific North America, Special Publication 35, Amer. Geog. Soc., 308 p. , and Marcus, M. G., 1964, Historical Variations of Lemon Creek Glacier, Alaska and their Relationship to the Climatic Record, Jour. Glaciology, vol. 5, no. 37, pp 77-86. Hoppe, G., 1951, Drumlins I Nordostra Norrbotten, Geograf. Ann., vol. 33, pp 157-165. ______, 1952, Hummocky Moraine Regions with Special Reference to the Interior of Norrbotten, Geograf. Ann., vol. 34, pp 1-72. , and Schytt, V., 1953, Some Observations on Fluted Moraine Surfaces, Geograf. Ann., vol. 35, pp 105-115. Ja c o t, H. F . , 1960, oral communication, Jewtuchowicz, S ., 1965, D escription of Eskers and Kames in Gashamnoyra and on Bungebreen, South of Hornsund, Vestspitsbergen, Jour. Glaciology, vol. 5, no. 41, pp 719-725. 224 Kaye, C, A., and Barghoorn, E. S., 1964, Late Quaternary Sea Level Change and C rustal Rise at Boston, M assachusetts with Notes on the Autocompaction of Peat, Geol. Soc. America Bull,, vol. 75, pp 63-80. Keith, M, L., and Anderson, G. M., 1963, Radiocarbon Dating Fictitious Results with Mollusk Shells, Science, vol. 141, no. 3581, pp 634-637. Kerr, F. A., 1936, Quaternary Glaciation in the Coast Range, Northern British Columbia and Alaska, Jour, Geol., vol. 44, pp 681-700. Klotz, 0. J ., 1899, Notes on Glaciers of Southeastern Alaska and Adjoining T e rrito ry , Geog. Jo u r., vol. 14, pp 523-534. ______, 1907, Recession of Alaskan Glaciers, Geog, Jour., vol. 30, pp 419-421. Krinsley, D. B., 1965, Pleistocene Geology of the South-West Yukon Territory, Canada, Jour. Glaciology, vol. 5, no. 40, pp 385-397. Kupsch, W. 0., 1956, Crevasse Fillings in Southwestern Saskatchewan Canada, Verk. K. Nederlandsch Geologisch-Mijabouwkundig Genoot, Geol. Ser,, vol. 16, pp 236-241. Lanphere, M. A., MacKevett, E. M. Jr.., and Steam, T. W., 1964, Potas sium Argon and Lead Alpha Ages of Plutonic Rocks, Bokan Mountain Area, Alaska, Science, vol. 145, pp 705-707. LaPerouse, J.F.G., 1799, A Voyage Around the World: London, pp 364-416. Lawrence, D. B., 1950, Estimating Dates of Recent Glacier Advances and Recession Rates by Studying Tree Growth Layers, Trans. Am. Geophy. Union, Trans., vol. 31, no, 2, pp 243-248, ______, 1950, Glacier Fluctuations for Six Centuries in South eastern Alaska and I ts Relation to Solar A ctiv ity , Geog. Rev., vol. 40, no. 2, pp 191-223. ______, 1953, Periodicity of Deglaciation in North America Since the Late Wisconsin Maximum, Geograf. Ann., vol. 35, pp 83-104. ______, 1958, Glaciers and Vegetation in Southeastern Alaska, Am. Scientist, vol. 46, no. 2, pp 89-122. Lemke, R. W., 1958, Narrow Linear Drumlins Near Velva, North Dakota, Am. Jour, Sci., vol. 256, pp 270-233. Lewis, W. V., 1949, An Esker in Process of Formation, Boverbreen, Jotun- heimen, 1947, Jour. Glaciology, vol. 1, no. 6, pp 314-320. 225 Loewe, F ., 1966, Soil Development and Ecological Succession in a De g laciated Area of Muir In le t, Southeast Alaska, Ohio State Univ. Res. Found., Inst. Polar Studies, Rept. 20, pp 19-28. Loken, O. H., and Leahy, E. J., 1964, Small Moraines in Southeastern Ontario, Canadian Geographer, vol. 8, pp 10-21. Martin, L., 1913, Juneau-Yakutat Section (of Excursion C-8; Yukon and Malaspina), Internl. Geol. Congr., 12th Session Canada, Guide Book no. 10, Excursion C-8 and C-9, Ottawa, pp 121-162. McCullock, D,, Hopkins, D., 1966, Evidence for an Early Recent Warm Interval in Northwestern Alaska, Geol. Soc. America Bull., vol. 77, pp 1089-1108. McKenzie, G. D ., 1967, unpublished d isse rta tio n and oral communication. Meier, M. F ., 1951, Recent Eskers in the Wind River Mountains of Wyoming, Proceedings Iowa Academy of Sci., vol. 58, pp 291-294. , 1964, The Recent History of Advance, Retreat, and Net Budget o f South Cascade G lacier, Am. Geophy. Union Trans., vol. 45, p 608. Mercer, J. H., 1961, The Response of Fjord Glaciers to Changes in the Pirn Limit, Jour. Glaciology, vol. 3, pp 850-858. ______, 1964, oral communication. Merriam, C. W,, 1967, w ritten communication. M iller, D. J . , 1960, Giant Waves in Lituya Bay, U.S. Geol. Survey Prof. Paper 354-C, pp 51-80. Miller, M. M. , 1958, The Role of Diastrophism in the Regimen of Glaciers in the Saint Elias District, Alaska, Jour. Glaciology, vol. 3, no, 24, pp 292-297. , 1964, Morphogenetic Classification of Pleistocene Glaciations in the Alaska-Canadian Boundary Range, Proc. Am. Philos. Soc., vol. 108, pp 247-256. ______, 1964, Inventory of Terminal Position Changes in Alaskan Coastal Glaciers Since the 1750's, Proc. Am. Philos. Soc., vol. 108, pp 257-273. ______, 1967, w ritten communication. Morse, F ., 1908, The Recession of the Glaciers of Glacier Bay, Alaska, N atl. Geog. Mag., vol. XIX, pp 76-78. 226 Muir, J., 1893, Notes on the Pacific Coast Glaciers, Am. Geol., vol. XI, pp 287-299. ______, 1895, The Discovery of Glacier Bay, The Century Illustrated Magazine, May-October, 1895, vol. XXVIII, pp 234-247. , 1902, Notes on the Pacific Coast Glaciers, Harriman Alaska Exped,, vol. 1, pp 119-135. ______, 1915, Travels in Alaska, Houghton-Mifflin Co., Boston and New York. Ovenshine, A. T., 1967, unpublished manuscript, U.S. Geological Survey, Menlo Park, C alifo rn ia. Pierce, C., I960, Is Sea Level Falling or the Land Rising in Southeast Alaska, U.S. Dept. Comm., Coast and Geodetic Survey, 20th Ann. Meeting Amer. Cong, on Surveying and Mapping, March 20-23, 1960, pp 1-12. Porter, S. C., 1964, Late Pleistocene Glacial Chronology of North- Central Brooks Range, Alaska, Am. Jour. Sci., vol. 262, pp 446- 460. ______, and Denton, G. H., 1967, Chronology of Neoglaciation in the North American Cordillera, Am, Jour, Sci., vol. 265, pp 177- 2 1 0 . Preston, R. S., Person, E,, and Deevey, E. S., 1955, Yale Natural Radio carbon Measurements II, Science, vol. 122, pp 954-960. Price, R. J.,1962, oral communication. , 1964, Land Forms Produced by the Wastage of the Casement Glacier, Southeast Alaska, Ohio State Univ. Res. Foundation, In st. Polar Studies, Rept. 9, 24 p. ______, 1966, Eskers Near the Casement Glacier, Alaska, Geograf. Ann., vol. 48, pp 111-125. Ray, L. L., 1935, Some Minor Features of Valley Glaciers and Valley Glaciation, Jour. Geol., vol. 43, p 297. Reed, J. C., and Coats, R. R,, 1941, Geology and Ore Deposits of the Chichagof Mining District, Alaska, Am. Inst. Mining and Metall, Engineers, Tech. Pub., 1051, 20 p. Reid, H. F., 1892, Studies of Muir Glacier Alaska, Natl. Geog. Mag., vol. IV, pp 19-84. 227 Reid, H. F., 1896, Glacier Bay and Its Glaciers, U.S. Geol. Survey 16th Annual Rept. 1894-1895, Part I, pp 415-461. ______, 1897, Variations of Glaciers, Jour. Geol., vol. 5, p 380. , 1908, Variations of Glaciers, XII, Jour. Geol., vol. 16, pp 46-55. , 1913, Variations of Glaciers, XVII, Jour. Geol., vol. 21, pp 422-426. , 1915, Variations of Glaciers, XIX, Jour. Geol., vol. 23, pp 548-553. Rossman, D. L ., 1963a, Geology of the Eastern Part of the Mount Fair- weather Quadrangle Alaska, U.S. Geol. Survey Bull. 1121-K, 55 p. ______, 1963b, Geology and Petrology of Two Stocks of Layered Gabbro in the Fairweather Range, Alaska, U.S. Geol. Survey Bull., 1121-F, 50 p. Russell, I. C., 1892, Origin of Gravel Deposits Beneath Muir Glacier, Amer. G eol., vol. 9, pp 190-197. ______, 1897, Glaciers of North America, Ginn and Co., New York. Schytt, V., 1963, Fluted Moraine Surfaces, Jour, Glaciology, vol. 4, no. 36, pp 825-827. Scidmore, E. R ., 1896, The Discovery of G lacier Bay, Alaska, N atl. Geog. Mag., vol. VII, pp 140-146. Seitz, J. S., 1959, Geology of Geikie Inlet Area, Glacier Bay, Alaska, U.S. Geol. Survey Bull., 1058-C, pp 61-120. Sharp, R. P ., 1958, The L atest Major Advance of Malaspina G lacier, Alaska, Geog. Rev., vol. 48, pp 16-26. ______, 1958, Malaspina Glacier, Alaska, Geol. Soc. America Bull., vol. 69, pp 617-646. Sproule, J. C., 1939, The Pleistocene Geology of the Cree Lake Region, Saskatchewan, Roy. Soc. Canada Trans. 3rd s e rie s, vol. 33, sec. r , pp 101-109. Tarr, R. S., and Martin, L., 1906, Glaciers and Glaciation of Yakutat Bay, Alaska, Bull. Amer. Geog. Soc., vol. 38, pp 145-167. ______, 1913, Alaskan G lacier Studies, N atl. Geog. Society, Washington, D.C. 228 Taylor, L. D., 1962, Ice Structures, Burroughs Glacier, Southeast Alaska, Ohio State Univ. Res. Foundation, Inst. Polar Studies, Rept. 3, 106 p. Theakstone, H. W., 1965, Contorted G lacial Lake Sediments and Ice Blocks in Outwash Deposits a t ^ ste rd a ls is e n , Norway, Geograf. Ann,, vol. 47, no, 1, pp 39-44. Tuthill, S. J ., 1966, Earthquake Origin of Superglacial Drift on the Glaciers of the Martin River Area, South-Central Alaska, Jour. , Glaciology, vol. 6, no. 43, pp 83-88, Twenhofel, W. S.,, 1946, Molybdenite Deposits of the Nunatak Area, Muir Inlet, Glacier Bay, U.S. Geol. Survey Bull. 947-B, pp 9-18. Ugolini, F. C., 1966, Soil Development and Ecological Succession in a Deglaciated Area of Muir Inlet, Southeast Alaska, Ohio State Univ. Res. Foundation, Inst. Polar Studies, Rept. 20, pp 29-56. Vancouver, G., 1801, A Voyage of Discovery: London, vol. 5, pp 421-422. W ahrhaftig, C ., and Cox, A., 1959, Rock G laciers in the Alaska Range, Geol. Soc. America Bull., vol. 70, pp 383-436. Wentworth, C. K., and Ray, L. L ., 1936, Studies of Certain Alaskan Glaciers in 1931, Geol. Soc. America Bull., vol. 47, pp 879-933, W illiams, G. H ., 1892, Notes on Some Eruptive Rocks from Alaska, Supplement II of Reid's Studies of Muir Glacier, Natl. Geog. Mag., vol. IV, pp 63-74. Wright, G. F ., 1887, The Muir Glacier, Am. Jour. Sci., vol. 33, pp 1-18, ______, 1889, The Ice Age in North America; D. Appelton and Co., New York and London. Wright, H. E. Jr., 1957, Stone Orientation in Wadena Drumlin Field, Minnesota, Geograf. Ann., vol. 39, pp 19-31. ______, and Ruhe, R. V., 1965, Glaciation of Minnesota and Iowa, in Wright, H. E., Jr., and Frey, D. G., eds., The Quaternary of the United States: Princeton, New Jersey, Princeton Univ. P ress, p 35.