This dissertation has been 64—7036 microfilmed exactly as received
LEWIS, Thomas Leonard, 1934— A PALEOCURRENT STUDY OF THE POTSDAM SANDSTONE OF NEW YORK, QUEBEC, AND ONTARIO.
Ohio State University Ph.D., 1963 G eology
University Microfilms, Inc., Ann Arbor, Michigan A PALEOCURRENT STUOY OF THE POTSDAITI SANDSTONE
OF NEU/ YORK, QUEBEC, AND ONTARIO
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Oegree Doctor of Philosophy in the Graduate School of The Ohio Stats University
• By
Thomas Leonard Lewis* A.B., M.S.
The Ohio State University 1963
Approved by
Adviser Department of Geology PLEASE NOTE: Figure pages are not original copy. They tend to "curl". Filmed in the best possible way. University Microfilms, Inc. ACKNOWLEDGMENTS
The writer wishes to thank the Bownocker Fellowship
Fund, the Orton Fund, and the Research Foundation of The
Ohio State University, for monies to defer costs of thin
sections, mao reproductions, and computer programing.
The Pennsylvania Glass Sand Corporation supported two
summers of field work, for which the writer is grateful.
Sincere gratitude is expressed to Dr. Robert L. Bates
for his guidance in this project. Appreciation is
extended to Dr. G. E. Moore, Jr., and Dr. H. J. Pincus
of The Ohio State University and Dr. Robert G. Sutton
of the University of Rochester for their valuable
discussions on various aspects of this work. Appre
ciation is also extended to my wife, Dorothy, for her patience and inspiration to the writer.
i i CONTENTS
Page ACKNOWLEDGMENTS ...... ii
CONTENTS ...... ill
ILLUSTRATIONS ...... v
TABLES ...... viii
INTRODUCTION ...... 1
AREA OF STUDY ...... 3
METHODS AND SCOPE OF THE STUDY ...... 6
DISCUSSION OF NOMENCLATURE ...... 10
PREVIOUS WORK ...... 15
PRIMARY CURRENT STRUCTURES ...... 10
Cross-bedding ...... IB
Classification ...... 20
Description ...... 21
Thickness ...... •... • 36
Regional analysis of dip azimuths ... AO
Inclination ..... 50
Topographic control ...... 52
Origin ...... 56
Ripple Marks ...... 65
Classification ...... 65
Description ...... 66
i i i Page
Regional trends ...... 71
Regional analysis ...... 77
Primary current lineation ...... 79
SECONDARY STRUCTURES ...... 00
Pseudo-ripple marks ...... 00
Pseudo-cross-bedding ...... 91
PETROGRAPHY ...... 94
Thin-section analysis ...... 95
Classification ...... 96
Regional variations of composition
and texture ...... 101
Heavy-mineral analysis ...... 105
CONCLUSIONS ...... 109
History of deposition ...... 110
Evaluation of procedures ...... 114
APPENDIX ...... 120
0IBLI0GRAPHY ...... 137
AUTOBIOGRAPHY ...... 148
iv ILLUSTRATIONS
Plate I (in folder) Cross-bedding dip azimuth distri bution in the Potsdam (Nepean) formation, New York, Ontario, and Quebec.
Plate II (in folder) Distribution of paleocurrents in the Potsdam formation.
Figures PagB 1 General map of study area ...... 4
2 Facies relations of Saratoga Springs group, Adirondack border, New York ...... 14
3 Index to published geologic maps showing Potsdam outcrop patterns 16
4 Location of Potsdam exposures showing prevalent cross-bedding ...... 19
5 Cross-bedding types dominant in the Potsdam formation of New York, Ontario, and Quebec ...... 22
6 Longitudinal section of planar cross bedding, Hammond quadrangle, New York ...... 23
7 Curved lower bounding surfaces of festoon troughs as seen in section cut normal to current direction, Hammond quadrangle, New York ...... 25
3 Crescent-shaped patterns of festoon cross-bedding in planed view ... 26
9 View of festoon cross-bedding showing opposing current directions, Chateaugay quadrangle, Quebec, Canada ...... 23
v figures Page 10 Exposure of a single festoon cross bed with current ripple marks, Lachlne quadrangle, Quebec, Canada ...... 29
11 Transverse section of large-scaled festoon cross-bedding, Nicholvilla quadrangle, New York 30
12 View parallel with the axis of festoon cross-bedding, Nichol- ville quadrangle, New York ..... 32
13 Herringbone structure, Chateaugay quadrangle, Nbw Yor k .... 34
14 Rose diagrams showing distribution of cross-bedding thicknesses in the Potsdam formation ...... 38
15 Vector means of cross-bedding dip azimuths in the Potsdam formation ...... 46
16 moving average of Potsdam cross bedding vector means ...... 49
17 Distribution of cross-bedding azimuths Ulestport area, Ontario, Canada ...... 54
IB Oscillation ripple mark, St. Canut, Quebec ..•••...... 68
19 Oscillation ripple mark, Port Henry quadrangle, NewYork ...... 69
20 Interference ripples, Dannemora quadrangle, NewYork ...... 70
21 Current ripple mark, Port Henry quadrangle, NewYork ...... 72
22 Current ripple mark, Dannemora quadrangle, NewYork ..... 73
vi Page Close superposition of oscillation ripples at nearly right angles, Dannemora quadrangle, Nee York • 74
Superposed oscillation and current ripples at right angles, Port Henry quadrangle, Nee York .... 75
Pseudo-ripple mark, Hannaea Tails, Potsdam quadrangle, Nee York ... 91
Plane-table map shoeing relations of pseudo-ripple marks, ripple marks, and cross-bedding in channel of the Raquette River, Hannaea Tails, Nee York ...... 83
Pseudo-ripple marks crossing ripple marks, Hannaea Tails, Potsdam quadrangle, Nee York ...... 84
Dipping strata faulted against horizontal beds (background), Hannaea Tails, Potsdam quad rangle, Nee York ...... 35
Detail of fault contact shoeh in Tig. 28 ...... 86
Oblique viee of p3eudo-ripple mark .. 87
Cross-sectional vise of pseudo ripple mark ...... 87
Detail of thin section across pseudo ripple mark fracture ...... 89
Loe-angle fracturing or pseudo-cross bedding in the Potsdam sandstone, Nicholville quadrangle, Nee York 92
Composition of the Potsdam sandstone 97
Teldspar content of the Potsdam sandstone ...... 102
Variation in the degree of roundness in the Potsdam sandstone ...... 106
v ii TABLES
Page 1 References for published maps ...... 17
2 Relative frequencies of cross-bedding types ...... 35
3 Per cent frequency of cross-bedding thickness by area ...... 37
4 Average measurements of ripple marks for arbitrarily grouped localities ...... 57
5 Cross-bedding statistics ...... 121
6 Petrographic composition of Potsdam sandstone ...... 129
7 Textural maturity of Potsdam sandstone ... 132
8 Heavy-mineral analyses (in per cent) of the orthoquartzite facies. Alexandria Bay and Hammond quadrangles. New York 135
9 Heavy-mineral analyses (in per cent) of the subarkose facies. Dannemora quadrangle. Cadyville. New York .... 136
v i i i INTRODUCTION
Nlany valuable paleocurrent studies have been made in recent years. When integrated eith stratigraphic data and petrographic analyses, they have proved useful in providing details about provenance, paleoslope, and direction of transport of clastic rock units. Cross bedding studies have had the major emphasis. Papers that appeared prior to 1955 are listed by Potter and
Olson (1954, p. 50-51), and by Potter and Siever (1956, p. 230). Notable additions to the literature since 1955 are papers by Pelletier (1958) and Vaakel (1962). These authors have combined petrographic, stratigraphic, and paleocurrent analyses in evaluating the distribution and depositional history of sand bodies in the central
Appalachians.
In a current-trend study of the basal Cambrian
Tapeats sandstones (northern Arirona) overlying a long- eroded Precambrian surface, fflcKee (1940) and mckee and
Reasar (1945) found irregular variations of cross-bedding trends which were caused by topographic differences on the surface on which the sandstones were deposited. It was thought by the present writer that studies of the
1 2
Potsdam sandstone might be fruitful in further evaluation of such control.
Regional stratigraphic relations of the Potsdam sandstone have suggested to investigators in the past that the formation represents an east-west marine trans gression around the Adirondacks and into the St. Lawrence
Lowland. However, suggestions as to source area have been conflicting. Little is known about the possibility of multiple sources or multiple environments of deposition.
5ince recognizable marine fauna are limited to roughly the upper half of the formation, it is questionable whether all the Potsdam is marine. In addition, little is known about the extent of marine onlap onto the
Adirondack surface.
Regional stratigraphic data on the Potsdam sandstone are inadequate, and well data are poor. In addition, there is little vertical change of lithology in the
Potsdam that might be useful in correlation and a minimum of evidence bf interfingering of beds. Evidence of a major source material for a mature sandstone, apart from the important shield areas, is also lacking. It was thought that a reconstruction of the regional pattern of sediment transport, based on a study of cross-bedding and other primary current lineations, and integrated with the regional sedimentary petrology, would be of value. AREA OF STUDY
The area of thia raport la limited by tha 42°45' and 46°00* parallala and by tha 70°15* and 76°30' meridians. It llaa in New York, Ontario and Quabac
(Fig. l). Physiographically, tha area ia bounded by tha fllohaak River on tha south, Lake Champlain and the
Richelieu River on tha east, tha Laurantian Highland
(Canadian Shiald) on tha north, and the Rideau Lakes and other lakes north of Kingston, Ontario, on tha seat.
Several major positive areas of Pracaabrian rocks, and a asll-dafinad basin composed essentially of Paleozoic rocka, are included in tha area. The Adirondack Mountains of northern Naa York, and the Canadian Shield north of
the Ottaaa Rivar, are tha moat important positive regions.
The St. Lasrence Lowland, bounded by tha Ottaaa River and tha Canadian Shiald on the north and the St. Laerance
Rivar on tha south, is tha dominant basin. Tha western margin of thia basin la tha Frontanac axle, a positive area of Pracambrian rocka connecting tha Canadian Shield and tha Adirondack arch. A leaser axis, tha Baauharnola anticline, dafinaa tha basin on tha east. It connects
tha Canadian Shield and the Adirondacks along a line just seat of Montreal. Thia axis is covered by tha Potsdam
3 4
/ LAD I OUT AC 19
s * LEGEND i \ 'i ItN rtw Ordcvictcc / //// Nm m r I s/ijf/
Acitflc IM rvtnw GENERAL MAP OF STUDY AREA lHl*ilM r«tailt Mrwi« OrcfwiC* McMMdimanu F ig . 1 5 sandstone sxcspt in tha vicinity of the Lake of Teo
Mountains, vast of Montreal, ahara Precambrian rocka are exposed.
Exposures of the Potsdam sandstone in Nos York are located on tha flanks of tha Adirondack Mountains. From the northoaatern corner of Naa York, they continue northaard into Quebec. Exposures appear on both aides of the St. Laerence Rivar aouthaeat of Montreal and than trend northeastaard along tha margin of the Precambrian
Shield. In Ontario, the Potsdam ia limited to the aeatern and northaestern edge of the St. Laarence
Loaland. Exposures occur northeast of tha city of Ottaaa, in Nepean toanahip aouthaast of Ottaaa, and than trand southaard to tha St. Laarancs River along the eastern margin of the Frontenac axis. IDE T HO OS AND SCOPE OF THE STUDY
Available exposures of tha Potsdam aandstona mere examined for oriantad primary bedding-plane structures, in particular for cross-bedding and rippla marks.
General lithology mat noted and textural examinetlone mare made at each locality. Particular attention mas paid to contact relatione of Potadam and Precambrian rocka and to the firat fern feat of Potadam aedlmenta exposed above a concealed contact. A fern good expoeures of parte of tha Potadam occur in atraam sections, although in moat areaa only a fee feat of just the top aurfacee are expoaed. Lack of vertical expoaurea restricted detailed etudiea that could be conducted in vertical eection.
An attempt maa made to eacure a uniform distribution of observation points throughout the total area, although no sot aelactlon pattern maa used (e.g., as suggested by Potter and Olaon, 1954). Establishing a uniform distribution maa difficult because soma exposure locali ties ora midely scattered and some parts of the northern outcrop pattern near the Adirondacks are covered by glacial debris. As many cross beds mers measured as
6 7 passible, again without reference to any predetermined
method of selection. Therefore, a complete record of
the total variability of cross-bedding azimuths was
determined at each observation point.'
At least two cross-bedded units were measured at
each exposure, and the total number of units was
generally greater than 2. Total readings for each
exposure ranged from 4 to 103,
Occasionally, only the traces of cross beds were
exposed in vertical section, and dip azimuth measurements
in the foreset planes could not be made. Traces of
cross-bedding had to be measured on two nonparallel
vertical cross-sections. Since two cross-bedding traces
(on two nonparallel vertical surfaces) define a plane,
the field notebook was oriented to this plane and the
strike and dip of thB plane recorded. These measurements
gave a reasonable estimate of the true cross-bedding
attitude. As many different traces as possible were
measured in this manner for each unit. At a few places,
the apparent dips of the bedding in two vertical
cross-sections were measured, and the true dip direction
was computed with the aid of the Schmidt stereonet. Dip
directions that could be determined in plan view on the
top of an exposure were measured directly. In several localities it was necessary to make rotation corrections for tilting. Procedures suggested by Haff (1938) were used. Cross-bedding poles were plotted on the stereonst and then rotated to the horizontal about the strike of the bedding. At most places, however, the Potsdam is horizontal or nearly so.
All field measurements of cross-bedding azimuths were recorded in an assumed down-current direction.
These measurements were plotted in 30-degree segments of a circle, percentages of measurements in each section were then computed, and circular histograms were drawn.
These histogrsms were plotted on a regional map (Plate I).
In order to establish a more interpretive regional pattern than that which the circular histograms show,
a computer program was formulated and individual cross
bedding azimuths were vectorially summed for every
locality. The resultants (vector means) were plotted
regionally. These vector means represent both the
average current direction and the magnitude or consis
tency of that direction. In order to minimize local
variations and to expand tha regional pattern, a moving
average was computed for the total exposure area. Mean
averages for four adjacent 15-minute quadrangles were
again summed trigonometrically and the average plotted
at tha center of the four-quadrangle grid. By moving 9 tha grid in any direction and utilizing it four times, as described by Pelletier (1958, p. 1035-36), a general end elightly expended regional paleocurrent pattern was constructed.
Thickness of cross-bedded units was also measured wherever possible. Values of thickness were then plotted in four size groups, and rose diagrams were drawn for each group. This was done for eight arbitrary divisions of the regional map. The rose for each thickness group was then compared with those computed from cross-bedding azimuths reed from the tops of exposures, and variations, if any, were noted.
Orientation of ripple marks was also analysed.
Determinations as to type were made in the field by noting surface configurations and by examining cross- sections. Other features, such as amplitude and distances between crests, were also noted. Orientations were not statistically treated, although they were plotted regionally to show variability or similarity with cross bedding averages (Plate II). Bedding traces in some examples were obliterated by cementing agents. DISCUSSION or NOMENCLATURE
Emmons (1838) first dsscrlbsd tha Potsdam sandstone from exposuras south of Potsdam, St. Lawrance County,
Nam York. Subsaquant early tracing of the Potsdam sandstone ess carried but by Emmons (1842) in Essex
County near Laks Champlain, Mather (1843) near Whitehall and Fort Ann southeast of Lake George, Brainerd and
Ssely (1890) along the Lake Champlain valley, Merrill
(1899) in Duchess, Washington, and Saratoga Counties, and Cushing (1894, 1895, 1897, 1901) in the upper
Champlain valley of Clinton County. Cushing (1905),
Cushing et al. (1910), and Cushing (1916) traced the
Potsdam easteard across the northarn Adirondack border
to the Thousand Islands region. Miller (1919) concluded
that the Potsdam is eell represented in the Champlain,
Mohawk, and St. Lawrencs valleys. In the southeast,
outlisrs extend to Wells (Pleasant Lake Quadrangle),
Hamilton County, North River (Warren County), and
Schroon Lake (Essex County). The existence of Potsdam
in Canada was first noted by Logan (1842 and 1862).
Brainerd and Seely (1890), Merrill (1899), and
Clarke and Schuchert (1899) described the Potsdam
formation as including limestones as well as basal
10 11 conglomerates end red end white massive sandstonea.
More accurate work by Cushing (1895, 1897, 1901) allowed
the differentiation of e series of passaga beda,
lithologically different from the Calciferous above and
the Potsdam below. Cushing (1908) introduced the term
Theresa formation for tha sandy dolomites and inter
calated thin sandstones of the passage beds on top of
the Potsdam sandstone. The contact waa considered to
be the base of the first dolomite layer. Later, Ulrich
and Cushing (1910) excluded the passage bads from the
Potsdam in the fflohawk Valley and applied the name
Theresa there. Cushing £t al. (1910) established the
correct order of strata from Potsdam to Theresa in the
Thousand Islands rsgion.
Although Hall (1859) atated that tha Potsdam could
be recognized in Pennsylvania* Virginia, Iowa* Wisconsin,
and Minnesota, later work in these states has indicated
differencea in age and has rssulted in different nomen
clature. At present, tha term Potsdam sandstone is
restricted to strata in New York and southern Canada.
Several names have been applied to the basal eand-
atones becauae of variable upper and lower lithologies.
Emmona (1842) delineated two varieties of the Potsdam,
a granular, red variety near Potsdam end a harder and
more crystalline variety at Kaeseville near the north
western shore of Lake Champlain. The Kaeseville was 12 considered tha younger. Chadwick (1915) termed the
Kaeseville upper Potadam* and Cushing (1916) included a white sandstone in the Ogdensburg area in the Potsdam sandstone. Ailing (1919) and Chadwick (1920) surmised that this white Potsdam sandstone was the same as the
Keeseville eandetone. Chadwick (1920) suggested that an unconformity separated the white sandstone and the underlying red Potsdam sandstone and conglomerates.
Fisher (1956) stated that the red and white aandetonea interfinger and concluded (1962) that the Kaeseville is not a valid unit and a division between the red and white sandstones is not practical.
most geologic maps of the western St. Lawrence
Lowland* based on geology by A. £• Wilson, designate the basal sandstone as the Nepean formation* named from
Nepean township* southwest of Ottawa. According to
Wilson (1946)* the Nepean Includes all the sandstone in this region formerly designated as Potsdam* plus a series of sandy dolomites (the march formation).
Other Canadian geologists have not favored the term
Nepean. Keith (1946), for example, defines the basal sandstone in the Cananocque region as Potsdam. Sandford and Quillian (1959) recognize the basal sandstone as the
Potsdam sandstone in the subsurface vest of the Frontenac axis. 13
According to a recent correlation chart (Fisher,
1962), a natural genetic interval of Croixian strata is recognized on the southern and aoutheaatern flanks of the Adirondacks. The total facies collectively constitute the Saratoga Springs Group (Fig* 2). This group is transgressive towards the north and west* The
Theresa of the type locality in northeastern New York is Ordovician in age. The fflarch formation of Ontario is also Ordovician and is correlative with the type
Theresa* Since the Potsdam (Nepean) of Ontario ia also recognized as part of the transgression, which may be either Late Cambrian or tarly Ordovician in Ontario,
the need for two distinctive terms is obviated* LOWER ORDOVICIAN
CAMBRIAN UPPER CAMBRIAN o Nepean AIS EAIN O SRTG SRNS RU. DRNAK ODR NW YORK NEW BORDER, ADIRONDACK GROUP. SPRINGS SARATOGA OF RELATIONS FACIES Precambrian AlexandriaBay Clayton Theresa Fotsdam Modified from Fisher, 1962 SARATOGA SPRINGS GROUP RousesPoint Moores limestones 4 dolomites 4 limestones Lower Ordovician Theresa
Ritchie Is FortAnn GlensPalls EoytIs., dol
dol. Falls Little Utica, Falls Little SW PREVIOUS UiORK
No publication deals with the stratigraphy, petrology, and sedimentation of tha Potsdam in its entirety. ITtost reports are on areal geology by quad* rangle, devoting only a paragraph or a page or two to description. A summary of these reports and the locations of the respective maps is provided in Table 1 and figure 3. A few papers are concerned with contact relations with the Precambrian, notably those by
Cushing (1899), Harding (1931), Kemp (1896), Kindle and Burling (1915), A. E. U/ilson (1937), and ID. E.
Wilson (1921).
Publications dealing with petrology are few and incomplete. The best analysis has been made by Wiesnet
(1961), but the paper covers only thB Moores quadrangle.
Harding (1931), Fraser (1931), and Keith (1946) describe the petrology of scattered samples that are limited mostly to eastern Ontario.
Among primary sedimentary structures, only ripple marks have received any attention, principally by
E. ffl. Kindle (1914, 1917) and m. E. Wilson (1937). No description, classification, or orientation analysis of cross-bedding exists.
15 16
INDEX TO PUBLISHED GEOLOGIC MAPS SHOWING POTSDAM OUTCROP PATTERNS T able 1 17 References for Published Waps Used In This Study NEW YORK Alexandria Bay Cushing, H.P., et al.. 1910 Antwerp Buddington, A.F., T974 Briar Hill Cushing, H.P., 1916) Dietrich, R.V., 1957 Broadalbin Miller, W.J., 1911 Canton Chadwick, G.H., 1920 Chateaugay Nelson, A.E., et al,. 1956 Churubusco Postal, A.W., VShl Clayton Cushing, H.P., et al.. 1910 Dannemora Poetel, A.W., 1??2 Glens Falls Newland, D.H., and Vaughn, H., 1942 Grindstone Cushing, H.P., et al.. 1910 Hammond Buddington, A.F., T9a4 (tie lone Postal, A.W., et al.. 1956 Moores Wiesnet, D.R .,"T96l Nicholvilla Postal, A «W., et a h , 1959 Ogdensburg Cushing, H.P,,” T916 Port Henry Kemp, J.F., end Ruedemann, R.f 1910 Potsdam Reed, J.C., 1934 Saratoga Cushing, H.P., and Ruedemann, R., 1914 Ticonderoga Newland, D.H., and Vaugtan, H., 1942 Whitehall Newland, D.H., and Vaughan, H., 1942 Willsboro Buddington, A.F., and Whitcomb, L., 1941
Unmapped quadrangles containing the Potsdam formation F onda No reference Fort Ann (East of Glens Falls) see Flower, R.H 1947 Moira (North of Nicholville) No reference Plattsburg (North of Willsboro) No reference Rouses Point (East of Moores) No reference CANADA Map 852-A 0ttawa-Cornwall, Ont. and Que. Wilson, A.E., 1946 Map 103B-A Ottawa 1954 Map 588-A Ottawa 1940 Map 413-A Ottawa (East half) 1938 Map 414-A Ottawa (West half) 1938 Map 5B7-A Caaselman, Ont. and Que. 1940 Map 710-A Prescott, Ontario 1942 Map 660-A Valleyfield, Que. and Ont. 1941 Map 661-A Maxville, Ont. and Que. 1941 Map 662-A L'Original, Ont. and Que. 1941 Map 1089-A Perth, Ontario Dugas J., 1961 Map 28-1059 Westport, Ontario Wynne-Edwards, H.R., 1958 Map 1946-9 Southeastern Ontario Keith, M.L., 1946 Map 1923-1 Cole, L.H., 1923 PRIMARY CURRENT STRUCTURES
Primary currant structural includa cross-bedding* ripple marks* and primary currant linaation. Each is discussed in a separate section.
Cross-bedding
Cross-bedding has long been recognized in the
Potsdam sandstone and this feature is measurable at more than 130 widely scattered localities (Fig. 4).
However, no adequate description or classification of the cross-bedded units has been established. In addition* no regional pattern of dispersal has been mepped nor has
the variability of dispersal directions been computed.
A number of factors had to be taken into consider ation before actural measurement. Large* partially buried blocks of the Potsdam have been moved out of their
original position by glacial actions locally* rotational movement by faulting is apparent. At some exposures*
bedding planes are masked by cementation or by staining
by iron oxides in bands that often do not follow true
bedding but may simulate inclined or contorted bedding.
After recognition of these features* procedures for
18 19
M CA LOCALITY wmm m t a (TATKTICMJ.T AMM.T
LOCATION OF POTSDAM EXPOSURES SHOWING PREVALENT CROSS-BEDDING . ______F | S 4 20 measuring croaa-badding were folloaad as dascribad previously (see methods and Scope).
Three significant properties of cross-bedding include thickness, dip azimuth, and variability of both thickness and dip azimuths. Thickness is the largest vertical measurement of a cross-bed between either successive croas-beds or flat planar surfaces at the top and bottom of the cross-bed unit. Dip azimuth is the direction of the maximum angle of dip. Variability is a measure of the changes of thickness and dip azimuth vertically in section and over a regional area and they reflect the stability of current velocity and
current direction. Similarities and differences in
these characteristics were studied regionally.
Inclination of individual cross-bedded sets waa also
analysed.
Classification
A descriptive classification by McKee and Weir
(1953) offers a standardized terminology, and it is the
principal classification referred to in the more recent
literature. Three major cross-bedding classes are
described, namely planar, trough, and simple based on
character and arrangement of the cross-beds. The
principal discriminating factor ie the character of the 21 lower bounding surface of the sets of cross-strata•
The lower bounding surfaces of planar (Fig. 5) and trough cross-bed sets are planar and curved surfaces of erosion respectively, whereas the lower bounding surfaces of simple cross-bedded sets are nonerosional surfaces.
The term festoon (after S. H. Knight, 1929) is applicable to the classification of Potsdam cross-bedding.
McKee and Ufeir (1953, p. 387) recognize it as a variety of trough cross-stratification that consists of cross cutting, semi-ellipsoidal troughs (Fig. 5).
Only planar and festoon cross-bedding are recognized in the Potsdam formation (Fig. 5). Approximately 57 per cent of the total cross-bedding is planar, and 43 per cent is festoon. Four per cent of the festoon cross-beds are large-scaled (greater than 2 feet thick and generally exceeding 20 feet in length). The remainder is less than one foot thick and generally less than 6 feet in length.
Description
Planar cross-bedding occurs if the lower bounding
surface is a planar surface of erosion caused by beveling
and subsequent deposition (McKee and Uleir, 1953, p. 385).
The shape of the cross-strata seta is tabular (Fig. 6).
Some planar cross-bed sets have tabular, nearly parallel 2 2
Horizontal section
Dip direction of unit C
Thickness of unit B
-r~
Dip direction of unit B
Longitudinal section Transverse section
PLAHAH CROSS - B3DDHIG The lower hounding surfaces are planar surfaces of erosion t
Dip directions of units
Traces of axi:
— Greatest thickness of festoon
FEST001J CROSS - B3DDI1IG The lower hounding surfaces are curved surfaces of erosion
CROSS-BEDDHJG TYPB2 DOLUITAIIT HI TIE POTSD/iL FORMATION OF IIS1:/ YORK, ONTARIO, A1ID QUEB3C
Modified fron McKee and V/eir, 1953, and. Petti John, 1957 23
Fig. 6. Longitudinal aactlon of planar croaa*baddlng, Haaaond quadrangle, Naa York planet, which show consistent inclination and are sharply truncated at both top and bottom, float cross- bedded units, however, show the foreset laminae sharply truncated at the top and slightly tangential at the bottom. Bottomset and topset beds are always lacking.
Horizontal traces may be linear or they may show a large radius of curvature concave in a downcurrent direction.
The lengths of most planar cross-strata range from a few inches to 2 or 3 feet. Only a few exceed this limit.
One example is about A feet thick and approximately
23 feet long.
Small-scale festoon cross-bedding is a common feature.
The elongate, semi-ellipsoidal troughs plunge in a down- current direction and the cross-beds conform with the walls of the trough. The lower bounding surfaces are curved and the troughs are nearly symmetrical when viewed in sections normal to the current direction (fig. 7).
In sections parallel to the axis or nearly so, the cross-beds are concave upward. Inclination of the beds is relatively high at the upper end of the trough but
It rapidly decreases down the plunge. In plan view,
the cross-beds show a crescent-shaped pattern (Fig. 8).
Younger laminae overlap older laminae on the concave or
downcurrent sidB of the crescent. Commonly, the troughs
occur in groups, sometimes in rows, and the crescents
are often cut off by succeeding younger ones. Occasion
ally, a complete trough occurs singly. 25
Fig* 7. Curved lover bounding ourfoeoo of footoon troughs ss soon in sootlon cut norosl to current direction, Haaaond quadrangle, Nee York. Length of pencil ie 6 inches. Figures heve no signifi cance. 26
Fig* 8. Crucint-ihapid pittirni of faatoon croaa-badding In plan via*. Nota tha lataral cut-off by a aacond faatoon* 27
The crescents sre generslly 3 to 5 feet side, though some rssch 15 feet. The width or rsdius of curvsture may vary widely in different units at a single exposure, but it is consistent within s single cross-bedded unit.
Thickness ranges from a few inches to 1 or 2 feet. If a trough is not cut off by succeeding younger ones, the length usually is the largest dimension, fflany single examples, 2 to 3 feet in width and only a few inches
deep, show overall length of 15 to 20 feet. Some
troughs show reversals of dip direction when several
layers are partially exposed in horizontal section
(Fig. 9). Current ripples and mud-cracked surfaces are
often associated with single festoon troughs (Fig. 10).
Large-scale festoon cross-bedding occurs only in
the basal conglomeratic facies in the Nicholville
quadrangle (area 4, locality 7, on Fig. 4). Because of
the large size, details of the physical characteristics
in three dimensions were not seen in any single exposure.
The cross-strata sets appear to be wedge-shaped in
longitudinal section. The lower bounding surface is
curved in transverse section, normal to the direction of
current flow (Fig. ll). The axes appear horizontal, but
most units may plunge one or two degrees. The inclination
of the bods is generally 15 degrees or less. Thickness
averagas 3 feet, and ranges as high as six. Length of
individual cross-strata averagas approximately 10 to 15 rig. 9. Via* of foatoon croaa-badding ahaving oppeaing currant dlraetlana, Chataaugay quad- rangla, Quabac, Canada. rig. 10. Cxpoaura of • oingio footoon croaa-bad •ith currant ripplo aarka, Lachina guadrangla, Quabac, Canada* Coapaaa pointa doan-currant• 30
Fig. 11. Tranavorao taction of largo-ecolo footoon croea-bodding, Nicholville quadrangle, Nao York. 31 feet. Several exceed 20 feet. A complete horizontal trace was not seen. A reasonable estimate of theradius of curvature is 20 feet or greater. Part of the curva ture in the horizontal plane and the dip of the beds towards the axis from the side of the channel is illustrated in Figure 12.
Despite what appears to be a consistent direction of channeling and subsequent filling, dip directions may show a high degree of variation. Part may bB due to a measuring error in that the true axis and direction of dip could not be accurately determined.
Regardless of type of cross-bedding, longitudinal sections may shour cross-bedded units confined to a single layer and separated by horizontal beds; vertically successive cross-bedded units following the same directional trend; or cross-beds that may show succession but with reversals in trend. Cross-bedded units confined to single units are more typical of planar cross-bedding.
Separated cross-bedded and horizontally bedded units may have identical grain size, or, as is common in the
Brockville-Gananoque region (Fig. A, areas 5 and 6 along the St. Lawrence River), cross-beds are confined to siliceously cemented sandstones and horizontal beds to the intercalated calcareously cemented sandstones.
Successively cross-bedded units or cross-beds showing the same general dip directions are more typical of Fig* 12* Via* pirilUl aith tha axis of footoon croaa-baddlng, Nicholvilla quadrangla, Naa York* Nota dip of tho bada tovarda tha axia. Axis and dip diraetion ahaan by arraa. 33 festoon cross-bedding. Reversals of trend are common
to both planar and festoon cross-bedding in a few
exposures of the Potsdam. Direction reversals in
alternating layers causes a herringbone structure
(fig. 13). Despite the reversals, an average current
direction can be computed if a large number of measure
ments is taken, since one general current direction is
usually dominant over another. A major current direction
ia consistent aith other patterns in exposures in
surrounding areas.
Estimated percentages of cross-bedding types must
bs regarded es only approximate, festoon cross-bedding
is easily distinguishable in plan vie* and in transverse
section, but not in longitudinal section. The plunging
attitude of festoon cross-bads is not always recognizable
and the concave longitudinal traces of festoons are
easily confused with similar slightly concave traces of
planar cross-bedding. Confusion as to type arises when
neither the top nor the bottom of a cross-bedded set is
adequately exposed. Usually, enough of either top or
bottom was exposed so a reasonable measurement of
dip-azimuth could be made, but unless the crescent-shaped
festoon exposed in the horizontal traces was adequately
exposed, the cross-bed was classified as planar. The
43.5-per cent value for festoon cross-bedding is an
accurate minimum, since all festoons were unmistakably 34
Flg« 13. Herringbone structure* Chateaugay quadrangle, Nee York. 3 5 identified from the top. However, beceuee of poor differentietion of festoon end planar cross-bedding in longitudinal section, festoon cross-bedding may repre sent a greater percentage than is indicatsd.
Relative frequencies of cross-bedding types were grouped by areas (Tabla 2). minimum frequency values for festoons were used as basis of calculation. The reader is referred to Figure 4 for the location of areas.
Table 2
Relative Frequencise of Cross-bedding Types minimum Probable Ares festoon variety planer type (per cent) (per cent)
and 2 28.1 71.9
and 8 49.5 50.5
4 38.5 61.5
5 35.7 64.3
6 50.9 49.1
7 34.2 65. B
Although sreas 3, 6, and 8 show relatively high frequencies, no major regional variations are evident.
It is believed by the writer that the higher frequencies in these regions are due to sampling, in part because of 36 a greater number of observations in these areas, and part because of a greater frequency of exposures viewed from the top.
Thickness
Thickness is the largest vertical measurement of
a cross-bed between either successive cross-beds or
flat planar surfaces at the top and bottom of the
cross-bed units.
True thickness is indeterminate since topset beds
are never present and some erosion of foreset beds has
invariably occurred. Likewise, the relative amount of
erosion that took place on successive beds is also
indeterminate, for example, two vertically successive
cross-bedded units of equal thickness may show evenly
inclined bedding, but at different angles. The bed
showing lower cross-bedding inclination may be a result
of lessened current action at the time of deposition,
or of greater erosion down to more tangential beds at
tha bottom of the unit. Presumably, currentfe causing
the erosion of cross-beds had nearly the same velocity
as those that deposited the foresets. Probably current
action throughout successive beds of equal thickness did
not vary greatly. The thickness of cross-beds is
consistent within single exposures and probably current 37 velocities causing consistent thickness anywhere were nearly of the same magnitude* measurement of the
thickness of cross-beds then may be of some value*
The presence or absence of regional variations in
thickness have proved to be of some palsogsographic importance (e.g., in studies by Schwarzacher, 1953, and Pelletier, 1956).
Cross-bedding is generally of very small thickness
(Fig. 14). The thickness of 63 per cent of the cross
bedding is four inches or less, 26 per cent is five to
eight inches, 4 per cent nine to twelve Inches, and
7 per cent greater than twelve inches. Frequency
thickness distributions are plottad on Figure 14 by
areas and are listed in Table 3 by per cent.
Table 3
Per cent Frequency of Cross-bedding Thickness by Area (Figs. 4 and 14) Total Area 4" 5-8" 9-12" 12" Readings
and 2 03.2 14.1 2.2 1.1 92
and 8 61.1 25.4 3.9 10.8 307
4 26.8 32.5 7.5 32.3 80
5 59.8 28.1 6.0 7.0 388
6 71.8 24.3 2.0 1.3 397
7 56.0 30.1 4.4 7.3 69 f 4“ S-8" >tr TOTAL m h * TOTALO—* GRAND TOTAL O to c a AREAS V2
AREAS
IX) AREA 4
AREA 5
AREA S
AREA 7
ROSE d ia g r a m s s h o w in g distribution o f c r o s s - m in « « io BEDDING THICKNESSES IN THE POTSDAM FORMATION n iQ M t m c T w m r o o M i (REFER TO FIGURE 4 FOR AREA LOCATIONS) Fig, 14 39
Variations in cross-bedding thickness of the Potsdam seem to have little regional interpretive value. Direction and thickness are consistent in all areas except area 4
(Fig. 14). Here thirty-two per cent of the cross-bedding is greater than one foot in thickness, and approximately
40 per cent is greater than 9 inches. Area four ia adjacent to the north-central portion of the Adirondack border (Fig. 4). Comparison of dip azimuths for this area and for this thickness shows that major current directions are not consistent with thinner cross-beds and particularly the crescent-like festoons measured from the top.
A minor bimodal distribution occurs in areas 3 and
8 (Fig. 14). Here there are two oppositely-directed current modes for thicknesses greater than 12 inches
(10.8 per cent of total). The 9-12 inch group shows a better consistency with the measurements of thinner cross-beds and the festoon crescents. Groups 9-12 inches and greater than 12 inches of area 6 show extended major class intervals due to the low frequency of measurements. In all other areas, a reasonable similarity occurs between directions of festoons and planar cross beds regardless of thickness of the latter.
In some cross-bedding studies, a plot of regional variations in thickness has been of value. Schwarzacher
(1953, p. 326) and Pelletier (1958, p. 1043) found a 40 thickening towards the source area in the Cretaceous sands of Cast Anglia and in the Pocono sandstones of the central Appalachians respectively. On the other hand, Yeakel (1962, p. 1578) found no significant regional trends of thickness in the Tuscerora-Juniata-
Bald Cagle beds of the central Appalachians. Cxcept for local variations in area four, no general direction of thickening or thinning of cross-bedding can be established in the Potsdam sandstone.
Regional analysis of dip azimuths
The azimuths of dip for each locality were grouped into thrity-eix 10-degree class intervals by computer analysis. It was thought that a 10-degree interval would give the most accurate representation of frequency variation, but a regional plot of circular histograms based on this interval would have been impossible to read. Instead, twelve 30-degree class intervals were selected and the data for the three appropriate 10-degree intervale were grouped for each 30-degree class. Circular histograms or rose diagrams, computed on the basis of per cent of readings for each 30-degree class interval, were plotted for each locality on a regional map (Plate I).
The histograms show the regional trends of current direction, as well as local variations and occasional reversals in those trends. In general, cross-bedding 41 azimuths are at right angles to tha southern and eastern border of the Adirondack mountains. Northeast of the
Adlrondacks, the trend Is southeast to east. This trend
Is fairly persistent northward Into Canada. Exposures are scarce along the northern border of the Adlrondacks, but a general southerly trend with several reversals
Is noted. Southeastward and westward azimuths vrap around the northwestern border of the Adlrondacks. The direction is more southerly and only slightly southwest
In western Ontario. The southerly orientation is maintained in the Ottawa region with several modes directed slightly southeast.
Noticeable deviations, reversals, and bimodal distributions occur in the eastern outcrop area (Plate I).
Good examples are evident at a locality 10 miles north east of Glens falls} locality 14, 20 miles north of
Plattsburg and just south of tha Canadian border; a locality in Quebec marked 19, 10 miles north of the
Canadian border; localities marked 12 and 26 on lie
Perrot southwest of fflontreal; and two localities both marked 11 north of the Ottawa River. Along the northern
Adirondack border, a prominent reversal is at a locality marked 38, 15 miles east of Potsdam. In the western
outcrop area, most deviations occur north of the St.
Lawrence River in the east-west exposure belt 20 miles south of Perth. Several localities shoe a southeast trend against the general southeast and southerly trend.
Several reversals are noticeable in the southern part of the belt and in its easternmost extreme. One locality, marked 13f 15 miles northeast of Kingston, shoes a bimodal trend. A locality marked 30 shoes the only major deviation in the exposed belt southeast of
Ottaea•
Pelletier (1958, p. 1045) suggested that a bimodal distribution of cross-bedding azimuths may be due to inadequate sampling. This may be true in part, however, this eriter believes that the histograms shoe adsqustely ehat eas seen at those localities.
Sampling eas greater for some localities than other
In addition, stratigraphic position eas difficult to determine in individual exposures so the readings repre sent various vertical posit ions in the Potsdam. A composite section of 120 feet from the western outcrop area and a 200-foot section from the eastern belt (Fig.4 area 5, localities 11 and 16) area 3, locality 23) were checked at 40-foot intervals for changes in the major
30-degres class intervals. Ross diagrams of the sub divided intervals were compared with the histograms of
total measurements for these sections. In general, similarities were obvious and any differences in the 43 major histogram classes of the subdivided intervals were limited to the two 30-degree class intervals adjacent to the major class interval of the total
section. It was concluded that readings taken at
various atratigraphic intervals were fairly reliable
as indicators of the average current directions of the
total section. Probably any error would be limited to
the 30-degree class intervals immediately adjacent to
the major interval of the total. The writer realizes
that a comparison of vector means for each subdivision
with the vector means of the total section would be more
accurate, but vector means were not calculated for
subdivisions of these two section3.
Reiche (1938), Curray (1956), and Pincus (1956)
have indicated that a vector summation and a plot of
the vector moans is useful in presenting periodic data.
Reiche, Pelletier (1958), and Yeakel(1962) have used this
method successfully on cross-bedding analyses of the
Coconino, Pocono, and Tuscarora-Juniata-Bald Cagle
sandstones respectively. Such an analysis is advantageous
in that it shows the average current direction for each
locality. The resulting regional pattern is easily
readible and it tends to smooth out the local variations.
Each cross-bedding dip azimuth was considered a
vector with direction and magnitude. The sines and cosines
of each azimuth for a given locality wBre algebraically summed* Dividing the sum of sines by the sum of cosines gave a value of tangent for the azimuth of the
resultant vector. The angle of this azimuth is computed
from the tangent using standard tables. The vector is calculated as the square root of the sum of sines plus
the sum of cosines. ll/hen the resultant is divided by
the frequency of observations for the given locality and multiplied by 100, a measure of vector strength or
vector magnitude is obtained in per cent.
In outline form, the calculations are as follows
(after Pincus, 1956, p. 544-545; Curray, 1956, p. 119)t
$ Cos e
£ Sin ©
T anQ:
r
r a T X 100 azimuth from 0° to 360° of each observation or group of observations.
0 vector means or azimuth of resultant vector
r vector resultant, or vector sum of unit vectors
a vector strength
f frequency of dip azimuth readings 45
Laborious calculations were greatly facilitated by programing a computer analysis for use with the 7090
computer using the Scatran language. The vector means,
resultants, and vector strengths far each locality of
the Potsdam sandstone measured for cross-bedding are
presented in Table 5 (Appendix).
The vector direction or mean is the preferred
orientation of the corss-bedding azimuths at a given
locality. The vector strength is a measure of dispersion
or the consistency of the vector mean. If all dip
azimuth vectors had the same direction, the vector
strength would be 100 per cent. If the distribution
u/as uniform, all components would cancel each other out
during summation and the vector strength would be 0
per cent. In this case the vector azimuth could not be
determined. All Potsdam vector means have an inter
mediate vector strength. The lowest value for exposures
of greater than 10 readings is 6.72 p b t cent, the highest
97.71 per cent.
When vector means are plotted regionally two major
dispersal directions are evident and can be summarized
numerically (fig. 15). In the eastern half of the map
73.3 per cent of the vector means fall in the east-south
quadrant. Of the total, 45.1 per cent occurs in the
east-southeast octant* The remaining 27 per cent of the
total is nearly uniformly spread among the remaining 46
\ i •V I
r.
MILCS SCALt \ 80 40 / Z 2 0 *'* KCAN CROSS-BEDDING AZlt LENGTH PROPORTIONAL TO VECTOR MAGNITl
VECTOR MEANS OF CROSS-BEDDING DIP AZIMUTHS IN THE POTSDAM FORMATION Fig. 15 / 47
three quadrants. Tha main concentration of vector means in tha eastern map area is in tha east-south
quadrant (72.8 par cant), 48.6 par cent of ehich occurs
in the south-southeast octant. A total of 18 per cant
occurs in the south-southeast octant. Only sight par
cant of tha total is raprasantsd in tha combined
north-east and north-east quandrants.
Vector strengths era ralativaly high and fairly
consistent in magnitude in both halves of tha map. In
the eastern half 86,5 par cant of tha means have vector
strengths greater than 50 par cant and in tha eastern
half 91.5 par cent of the means are greater than 50
par cant. The same relative regional comparison is
maintained eith vector strengths greater than 70 per
cant. In a comparison of vector strengths greater than
90 par cant, tha eastern half of the map contains a
much larger percentage (34.5) than the eastern half
(13.1 par cent). This higher percentage in the western
half reflects the more accurate measurements and the
higher percentage of festoon cross-bedding in this
region. Areas 3, 5, and 6 (fig. 4) shoe the highest
vector strengths ehich similarly correspond to a greater
percentage of festoon cross-bedding, more accurate
measurements of that cross-bedding, and generally more
accurate sampling. 48
A moving average of cross-bedding vector meant was constructed as suggested by Pelletier (1958, p. 1036) and summarized graphically in figure 16. A moving average simplifies tha regional pattern by reducing local deviations, bimodal diatributiona and local reversals. However, certain grids contain more locality averages than others, thus unequal weight is put on these grids when tha moving average is constructed.
Noticeable effects may occur on the periphery of the map (fig. 16). Such edge effects may not bo noticeable as, for example, along tha western edge of the St.
Lawrence Lowland north of Lake Ontario (fig. 16) where
there is a large and even distribution of localities.
Edge effects on tha eastern and southeastern border of
the Adlrondacks are most noticeable due both to the wide scattering localities and to a high variance of vector means within those localities.
Currents moved easterly, southerly, and southeasterly away from the eastern and southern borders of the
Adlrondacks (fig. 16). Two major current trends are
evident in the north. In the northeast currants moved
easterly and southeasterly. This trend abuts against
tha Adlrondacks and is diverted south end aouthwestward.
A second trend on the west originates southsasterly in
tha vicinity of Ottawa and turns south and finally 49
%
I /
ON TAN IO
Qrld for constructing moving ovorogo. Arrow roprosonts tha trlgonomotrlcaliy summod / rosultont of locality moans 1-& \ Fig. 16
MOVING AVERAGE OF POTSDAM CROSS-BEDDING VECTOR MEANS 50 southeastward as it crossas tha St. Lawranca River, fflora southeastward trends are evident where currents abutted and wrapped around the northwestern Adirondack flank•
Inclination
Angles of repose for Potsdam cross-beds in sandstones range from 5 to 29 degrees and average 18.3 degress.
Eighty-eight per cent of the cross-beds dip from 14 to
29 degrees, 11 per cent less than 14 degrees, and approximately 1 per cent greater than 28 degrees.
Inclination of cross-beds varies depending on the
size of the clastic material, tha origin of the cross beds (whether aqueous or eolien), and the presence and
degree of post-depositional deformation.
Observed angles of repose are highest from coarse
gravels (42 and 41 degrees reported by Lahee, 1952, p. 299, and Thoulet, 1887, in Twenhofel, 1961, p. 8 3 f
38 degrees in rounded gravels, Potter, 1955). Cross-bed
inclinations in flat-lying sands and sandstones are
generally greater than 5 degrees but never exceed 34
degrees, the maximum angle of dry sand as reported by
Bagnold (1941, p. 201).
maximum anglea of inclination of flat-lying eollan
cross-bads may be higher than those deposited in a water
environment. Commonly, observed maximum angles range 51 from 30 to 33 degrees. Crtssey (1928) reports maximum anglaa of 32 degraea for the Indiana aand dunes.
Similarly, Kiersch (1950) found a maximum of 32 degrees for the Navajo sandstone. In the only comparative study,
NtcKee (1940) noted that the eollan Coconino sandstone ahoeed a maximum dip of 33 degroas ehareas the Tapeats and Supal sandstones, both deposited in water, showed maximum repose angles of 27 or 28 degrees.
Analyses of cross-bed inclinations in the Sturgeon quartzite (Trow, 1948), Baraboo quartzits (Brett, 1955),
Lorraine quartzite (Psttijohn, 1957b), Pocono formation
(Pelletier, 1958), and Tuscarora formation (Yeakel,
1962) show that some angles of repose may be extremely high because of subsequent deformation. In addition, it was found that average repose angles increase with greater degrees of folding.
The major grouping of Potsdam cross-bed inclinations compare fairly well with those of sandstone formations of aqueous origin. Potter (1955) found 95 per cent of readings between 6 and 30 degrees with an average of
16.5 degrees for the Lafayette formation. Four per cent ranged from 30 to 36 degrees but the total analysis included readings in intercalated gravels. Knight (1929) found 97 per cent of the readings of the Casper formation between 6 to 30 degrees with 1 per cent greater than 30 degrees (average 18 degrees). Unfortunately, 52 quantitative distributions of cross-bed inclinations ware not recorded for fflcKee's (1940) comparative study of the Tapeats, Supai, and Coconino sandstones. It is noteworthy that studies of cross-bed inclinations of folded fluvial or marina sandstones, even though all angles have probably been increased by deformation, show very high concentration of inclinations between
12 and 30 degrees, for actual percentage distributions, the reader is referred to analyses by Trow (1946),
Brett (1955), Pettijohn (1957b), Pelletier (195B), and Yeakel (1962).
On the basis of low maximum cross-bed inclinations
(99 per cent less than 28 degrees) and relatively similar averages with other studies of horizontal sandstones of known origin, it is concluded that the Potsdam cross-beds in sandstones are a result of deposition in a water-laid environment. No differentiation between fluvial and marine origin can be made on the basis of angles of repose•
Topographic Control
Current directions that were controlled by topo graphic irregularities on the Precambrian erosion surface occur locally. Observable topographic control of Potsdam cross-bedding is limited to a small region north of the 53
St. Lawrence River in areas 5 and 6 (Fig. 4). Notable control occurs in the Westport area, Ontario, adjacent
to and within the Frontenac axis region (Fig. 17). A general southwesterly trend is dominant in the northern part of the map area, although bimodal distributions
reflect some current reversals. One complete reversal
(marked 9) can be seen at the westernmost outcrop.
Noteworthy reversals occur in the east-central part of
the Uleatport map area. On the western margin of a
Precambrian knob, exposures marked 11, 15, 5, and 8
show trends to the northeast and one exposure (marked
12) trends to the north. Farther to the north on the
same Precambrian margin, a general southeast trend,
consistent with the regional trend, is noted at
exposures marked 57, 19, and 27. An exposure (marked
14) shows the same trend on the eastern side of the
Precambrian knob. Two isolated exposures, marked 35
and 14, are remnants of another southeastward projection
of Potsdam sediments on tha Frontenac axis.
At localities near the Precambrian contact, where
reversals ara common, cross-beds are sometimes scattered
vertically or confined to narrow stratigraphic zones
and are generally few in number. At most contact
exposures, sandstones immediately above thin basal
conglomerates show no cross-bedding. When present,
cross-beds are extremely thin in beds naar the Precambrian L•ESJ!
LZJroSttw wtmuL p C u t L t m . or umes
Dl Dtr AziMtmt DMKTIONL MIA IN m o no r m on or
DISTRIBUTION OF CROSS-BEDDING AZIMUTHS. r WESTPORT AREA. ONTARIO. CANADA Fig, 17 55 contact. Cross-beds higher in the section are thicker and ahos a more dominant orientation consistent with tha regional trend. There is no initial dip to Potsdam bads close to the contact, nor is thera imbrication of tha conglomerate pebbles filling small irregularities in tha erosion surface.
The cross-bed trends apparently indicate movement of marginal currants away from peninsular Precambrian knobs toearde centers of small, local smbayments. Lack
of pebble imbrication, frequent absence of cross-beds
in the lowest few feet of sandstones and their small
scale whan present, indicate low current action that
may have persisted in protected embayments developed
on tha frontenac axis. An increase In thickness,
frequency, and dominance of cross-bed directions higher
in the section indicate an increase of current velocities
and deposition in more open waters.
Topographic control in other parts of the Potsdam
is not evident. (Dost of the sandstone bada are horizontal
at or class to the contacts along the northwestern
Adirondack border, where, in the Alexandria Bay and
Hammond quadrangles, topographic relief on the Precambrian
is estimated at as much as 200 feet. Cross-bedding is
commonly lacking. When present, it shows trends that
seldom deviate from the regional pattern. 56
Origin
Reports by Passarge (saa Twenhofsl, 1961, p. 93),
Creasay (1928), Bagnold (1943), lahee (1941), and fflcKea
(1940, 1945, 1953) have shown that maximum inclination angles of lee-slopes of dunes predominantly range from
30 to 34 degrees. Experimental evidence (fflcKee, 1945) suggests major differences in repose angles of sand when deposited under subaerial and subaqueous conditions.
In grain sizes ranging from fine through coarse sand
(the size limits of most Potsdam material), average maximum angles ranged from 32 to about 35 degrees for angular subaerial sediments and from 24.5 to about 28
degrees for the same sediment deposited in water.
Rounded sands showed 30.3 to 32.3 degrees for subaerial
deposition and 23.6 to about 28 degrees for subaqueous
deposition. Repose angles may vary slightly because
of differences in grain size, roundness, and sorting,
but it Is evident that the maximum slope formed
subaerially Is consistently steeper than that formed
under subaqueous conditions.
Maximum inclination angles of cross-beds in Potsdam
sandstones do not exceed 29 degrees, and most are less
than 23 degrees. It is concluded that Potsdam cross-beds
were deposited in water. 57
ITIeans of differentiating between nonmarine and marine origin of cross-bedding have not been developed.
Pettljohn (1957a, p. 170) states that there are no known differences in thickness, variations in direction, or structure between nonmarine and marine cross-bedding.
Even the mechanics of formation of various types is not clear, although soma experimental work (fflcKee, 1945;
Schwarzacher, 1953) has helped in describing the physical controls necessary for the formation of cross-bedding.
The conditions are numerous, however, and each has
varying effects which make direct interpretation of
environments difficult. Supporting evidence from fossil,
isopach and lithofacies studies has been used to estab
lish fluvial or marine conditions.
Planar cross-bedding has been produced experimentally
in a standing body of water (lYlcKee, 1945). Progressive
slumping down foreset planes forms a series of cross
strata that slope uniformly in longitudinal section.
Any change in introduced material,such as grain size,
sorting, roundness, and supply of sediment, or any change
in the velocity of the currents, causes changes in the
angles of repose and produces beveling or truncation of
the dipping strata, major changes occur when the water
level is raised or lowered. If the level recedes,
either beveling or scouring develops on the original 50 set of sloping strata. If water level rises slowly, a series of flat-lying bads is formed. If the water rises rapidly, a new set of sloping foresats is produced.
According to Schwarzacher (1953, p. 325-326), thickness of units probably depends on height of the water level above the sand-water interface, relief of the bottom, and amount of sediment supplied.
McKee (1940) suggests that the repeated uniform planar cross-beds of the Tapeats formation, truncated by flat surfaces above and below, represent deposition in a sinking marine basin. Evidence of changing water levels helps corroborate this theory. On the other hand, planar cross-bedding has been noted in transverse bar deposits of the Mississippi River (McDowell, 1960), and the San Bernard River, Texas (Lane, 1963). Pelletier
(1950) indicates that 97 per cent of the planar cross- bedding of the Pocono formation originated in transverse sand bars, which formed during periods of flooding when sediment load and velocity of the streams were greatest.
Such conditions provided the truncation of cross-beds;
thicknesses comparable to cross-beds of present-day sand-bar deposits, laterally continuous cross-beds, and slight differences of direction in succeeding units.
Festoon cross-bedding has been produced experiment ally by stream currents (McKee, 1945). Troughs or
channels are formed by concentrated currents. The 59 channels are characteristically flat-bottomed, straight- walled, and shallow. If filling follows by a continuous flow of the currents that produced the channel, the original channel shape la not altered and the deposits made are essentially horizontal. These conditions occur when an increase in stream load or a decrease in velocity is responsible for deposition. If the water is allowed to rise after initial channeling, the walls slump, the trough becomes rounded, and deposits filling it conform to the shape of thB channel and produce festoon cross beds. Stratification varies in transverse section depending upon method of filling. If particles settle from above in quiet water, the trough la symmetrically filled; if currents move through the channel, the trough is symmetrically filled and the bottom strata are thickened; if currents move diagonally across the channel, the trough is asymmetrically filled.
festoon cross-bedding appears to occur in a variety of environments. McKee and Resser (1945) found some scouring characteristic of basal Tapeats beds near the flanks of monadnocks on the Precambrian surface. McKee
(1939) found that festoons or scoured-filled channels are prevalent in the Colorado River delta. Similar findings are reported by McDowell (I960) in the
Mississippi River, Lane (1963) in the San Bernard River, 60
Texas, and Briggs (1963) in tha Brazos River sandstone member of the Garner formation, Texas. A fluvial origin has been ascribed by Knight (1929) to large-scaled festoons of the Gasper formation, festoons comparable to the size of those in the Potsdam sandstone have been described by Stokes (1953) in the Salt Ufash sandstone member of the Morrison formation, and by Hamblin (1961a) in the Jacobsville sandstone of northern Michigan. Both authors suggest a fluvial origin. Hamblin (1961b) describes micro-cross-bedding of the festoon variety
(2.5 inches aide, 0.5 inch thick, 8 inches long) in
Keweenawan sediments of northern Michigan that mere supposedly formed in fluvial-plain or tidal-flat environments. Similar micro-cross-bedding has been observed associated uiith sole markings by the present writer in siltstone turbidities in the Upper Devonian beds of New York.
Thus festoon cross-bedding, and probably planar cross-bedding, are not distinctive of any particular environment. Apparently, energy levels and physical factors within any subaqueous environment control the development, size and type of cross-bedding. As regards festoon cross-bedding, Hamblin (1961b) suggests that, regardless of size, they may all be formed by one process) i.e., deposition on the lee slopes of migrating 61 sand bodies such as cusp ripples, crescent-shaped sand waves, and cuspate bars*
McKee (1940) Indicated that the degree of variation in orientation of cross-bedding may differ in various environments* The marine Tapeats sandstone shoes less variation than the eolian Coconino, but more than the deltaic Supai formation. Unfortunately, most other quantitative studies deal only with a single formation or similar environmental conditions through several formations (e.g., Yeakel, 1962, in the Bald Eagle-
Juniata-Tuacarora beds), and variations that do occur are nonsystematlc. Quantitative data from experimental and field studies of modern sediments is meager. McKee and Sterrett (1961) have reproduced primary structures of longshore bars and beaches but they make no systematic comparison of directional variations* Though deltaic
stream systems are often cited to account for cross bedding patterns, little direct comparison of ancient and present-day deltas can be made because of the
scarcity of quantitative directional data from modern
deltaic sediments.
It is concluded that both types of Potsdam cross- bedding were formed together and under essentially
similar conditions of current activity. There is
repeated alternation of types in most localities*
Planar cross-bedding may dominate at one exposure, but 62 exposures less than a mile away may shoe the festoon type. Absence of large variations in thickness among cross-beds of either type indicates similarities in current strengths, sediment supply, and depth of water.
Slight variations in inclination of foresets reflect variations in sediment supply and current velocity.
Truncation of ccoss-beds occurred when current velocity remained constant and supply was cut off or when a second current eroded the previously formed topsets.
Variations in water level and the rate at which it changed governed whether sets of cross-beds were
directly superposed or were separated by horizontal beds. Changes in water level may account for the channeling and filling of festoon scours.
Similar conditions of formation of cross-beds persisted vertically throughout the Potsdam formation.
Constant alternation of types, and similar thickness
and directional trends through a thickness of 240 feet
of Potsdam, indicate little variation in current movement.
This conclusion is in accord with those reached in other
quantitative cross-bedding studies. Brett (1955)
reported consistent dip azimuth directions in 4,000 to
5,000 feet of Baraboo quartzite. Pelletier (1958)
ehowed that the deviation of vector means at various
intervals throughout 1200 feet of Pocono beds varied 63 less than 20 degress from the vector mean of the total section, and Yeaksl (1962) described deviations of lass than 12 degrees of various Intervals for 1B00 feet of
Tuscsrora beds.
Tha presence of sparse marina fossils, oscillation ripple marks, and occasional dolomitic sandstones show that part of tha Potsdam formation was deposited in a marine environment. The physical characteristics of
Potsdam cross-beds also suggest such conditions of formation. These characteristics are as follows.
1. Numerous herringbone structures are present in both types of cross-beddingt many vertically adjacent sets of cross-beds show directions opposed nearly 180 degrees. Such conditions seem more likely to result from fluctuating tidal currents than from stream action,
2. There is a persistent lack of intercalated muds in the cross-beds and throughout the Potsdam. Fluvial scouring often develops in fine sands and muds, utith subsequent filling by sands. Potsdam scouring took place in sands with subsequent filling by sands.
U/innowing of fine sediments was probably accomplished by currents, and perhaps by waves in an open marine environment.
3. Fluvial and deltaic cross-beds characteristic ally increase in thickness in the up-current direction.
Lack of such regional variation in the Potsdam cross-beds 64 suggests that they were deposited under remarkably stable and unform conditions throughout their extent*
4. Except for a local conglomerate in the
Nicholvllle quadrangle, evidence of major fluvial sedimentation is lacking around the Adirondack border.
Bending of current trends around the northern side of the Adirondacks suggests that these mountains formed a positive region during deposition of the Potsdam.
However, these current-trend patterns give no evidence of any outpouring of sediments from high regions; the generally southward trends persist through coarse arkose and conglomerates as well as orthoquartzites.
These current trends probably represent redistribution of sediments under marine conditions rather than direct sedimentation from a positive region to a basin area.
5. Initial currents in small depressional areas of the Precambrian surface, such as the Ulestport area, were extremely weak. Higher in the section, there was a progressive increase of current strength and stability as conditions changed from a protected embayment to that of a more open environment.
Cross-bedding directional trends reflect current movement at the time of deposition and may or may not imply source areas. Presumably the Canadian Shield, the frontenac axis, and the Adirondacks all supplied sediments. An Adirondack source is implied on the 65 south and east sides of the mountains but not on the north side.
Current patterns between the Canadian Shield and
the Adirondacks indicate a general southward paleoslope, persistent throughout Potsdam time. Several current
sources may have existed along the Canadian Shield, but younger sediments in the central St. Lawrence Lowland
obscures a possible continuously shifting trend. The widespread and consistent pattern of Potsdam cross-beds
does not suggest major activity of local longshore currents.
Ripple Marks
Einmons (1042) first reported ripple marks in the
Potsdam sandstone. Most investigators since then have noted their presence, but none has discussed types, physical characteristics or orientation. Kindle (1914)
described Potsdam ripple marks from exposures near
Ottawa and suggested possible environmental inter pretations.
Classification
A study of 256 exposures of ripple marks in the
Potsdam sandstone shows that both oscillation and current
types are present. Oscillation ripples represent 32.7 66 per cent of the total, and current ripples 52,2 per cent. The remainder (15.9 per cent) could not be classified as to type because of post-Cambrian erosion and cementation, although enough of each exposure has been preserved so that orientation can be determined.
Description
Three characteristics were used in study and description of ripple marks. They are amplitude, or elevation of the crest of the ripple above the trough; wave length, the distance between adjacent crests; and ripple index, the ratio of wave length to amplitude.
Both types of ripple marks are small scaled.
Amplitude ranges from a minimum of 0.2 inch to approxi mately 2.0 inches although most measurements fall between
0*5 and 1.5 inches, minimum and maximum wave lengths are 1 and IB inches, but most are between 2 and 6 inches, most ripple index values lie between 3 and 8 although
they range from 1.4 to 11. Average values of these measurements for various grouped localities are presented in Table 4. 67
Table 4
Average Measurmenta of Ripple Marks for
Arbitrarily Grouped Localities
Number of Average Average Average individual wave Localities amplitude ripple ripples length (inches) index measured (inches)
1 - 4 15 0.66 2.7 4.1
5 - 10 26 1.30 5.6 4.3
11 - 19 48 0.97 4.9 5.1
20 - 22 15 0.74 4.1 5.5
23 - 32 19 0.92 3.9 4.2
33 - 43 15 0.88 3.7 3.9
44 - 48 12 0.56 2.8 5.0
Oscillation ripples occur In a variety of shapes*
Most varieties are modifications of the typical symmetri
cal ripple mark with angular crests and rounded troughs*
Many examples show crests that are rounded, but the
total symmetrical shape is preserved (Fig* 18)* Sometimes
the crest approach asymmetry because of a redistribution
of upper laminae by eroding currents* Commonly small
rounded crests are separated by flat-bottomed troughs
(Fig* 19)* The amplitude, wave length, and horizontal
trends are generally persistent over many feet of exposure.
Interference ripplee occur but they are not common and
generally are incomplete (Fig* 20). Fig. 18. Oscillation rlppls M r k v St. Canut Quabae (locality 22, Plata II). Craata arc roundad, but syMiatrieal ahapa of craata and trougha la aaslly aaan. Fig, 19. Oscillation rlpplo oarkt Port Honry Quadrangle, Noo York (locality 5, Plata II). Rounded craata ara aaparatad by flat-bottoosd troughs* rig, 20. Intarfaranca rlpplaa, Dannaaora QuadrariQla, Nao York (locality 7, Plata II)• 71
All currant rippla marks show an asymmetric cross-section, with a gentle up-current slope and a staap down-current slope (Fig. 21). Laminae In the crests resemble miniature cross-bedding, dipping down- current parallel to the ateep front slope. Some cross- sections show evidence of migration by a progression of superposed crest outlines, the lower crests being displaced in the up-current direction. Occasionally, coarser grains than those found in the crests are preserved in the trough areas. Horizontal patterns may be linear or curvilinear and they often persist over many feet of exposure. Frequently, a pattern is broken forming angular apexes in either the up-current or down-current directions (Fig. 22).
Regional Trends
Oscillation and current ripples are found together in many exposures. Rippled surfaces may be separated vertically by many feet of sediment, or closely superposed upon one another, often at nearly right angles (Fig. 23).
Variations in direction are frequent between adjoining current-rlpple sets, oscillation-ripple sets, or mixed- ripple sets. Greatest variations in orientation are most common among superposed mixad-ripple sets (Fig. 24). Tig. 21. Currant rippla nark, Port Hanry Quadrangla, Naa York (locality 5, Plata II). Doan-eurrant dlraction la toaard tha handla of tha haaaar. Fig* 22. Currant ripple nark, Dannenora Quadrangle, Naa York (locality 7, Plata II). Blada and of chlaal pointa doan-current. Note apex (cantar) pointing in up-current direction. Fig. 23. Close superposition of oscillation ripploo ot noorly right angles, Danneaora Quadrangle, Nov York (locality 5, Plata II). Vortical distance bstooen bads* 2 inches. Fig. 24. Superposed oscillation and currant rlpplaa at right angles, Port Honry Quadrangle, Noo York (locality 5, Plato II), Oscillation ripplo direction is left to right (i to C) and currsnt-rlpplo direction is froo top to bottoo (N to S)• Vertical distance bstossn beds * 2 inches. 76
Ripple marks are distributed over most of the
Potsdam outcrop pattern (Plate II). Some exposures close to ancient land masses show a greater frequency of the oscillation type (e.g., Plate II, localities 2f 6, 7,
9, 10, 21, 22, 23, 26, 32, 33, 37, 41, 46), whereas others equally close show a higher frequency of the current type
(e.g., localities 1, 3, 4, 25, 28, 29, 30, 42, 43, 44,
45). Part of this inconsistency may be because measure ments at the latter localities were made in beds stratigraphically higher. It is noteworthy that exposures
8, 11 to 13, and 17 to 20, which are farther from
Precambrlan masses and presumably higher stratigraphic- ally, show a greater frequency of current ripple marks.
Oscillation ripples show the greatest variation of direction with cross-bedding means* A few examples include exposures 4, 9, 10, 19, 23, 24, 29, 37, 41, 43,
44, and 48. At exposures showing only oscillation ripples, directions may be fairly consistent (as in exposures 4, 6, 7, 10, 41, 44) or show a high degree of variation (as in 22, 32, 33).
At most exposures, current ripples trend consistently with cross-bedding vector means for the same exposure.
The spread may be high for some localities (e.g., locality 17), but the amount of dispersion is also high for the cross-bedding, aa shown by the relatively low 77 vector magnitude (approximately 50 per cent). Other exposures, such as 5 f S, 25, 28, 30, 31, 42, 44, and
45, shoe a close psrallelism of current ripple trends and cross-bedding vector means eith higher vector magnitudes. Several examples, notably 3, 12, and 18, show a high degree of variation with cross-bedding, which may be a result of several major current systems.
Regional Analysis
A survey of the literature on regional analyses of ripple-marks in sandstones shows that it is much more vsriable in orientation than cross-bedding. Oscillation ripple marks may or may not parallel ancient shorelines.
Current ripples, which are considered by many as reliable indicators of current trend, may support or conflict with the results of cross-bedding studies.
Hyde (1911) showed that oscillation ripples of the
Bedford and Berea formations of central Ohio showed a preferred orientation parallel to the shoreline.
Van Sertsbergh (1940) described some oscillation ripple marks oriented parallel to cross-bedding patterns and
some current ripples oriented normal to these patterns.
Trow (1948) found that some oscillation ripples of the
Sturgeon quartzite were parallel and others normal to
cross-bedding currents, and the few current ripples 78 measured never folloeed the cross-bedding trends.
Pelletier (1958) found only a fee current ripples in the
Pocono beds, all of which were normal to cross-bedding trends. On the other hand, Yeakel (1962) found 22 of
41 ripples within 30 degrees of mean cross-bedding azimuths, and fflclver (1961) found all current ripples
(100 readings in the ITIartinsburg formation) consistent within 32 degrees with current directions from flute casts.
Oscillation ripple marks of the Potsdam formation are not entirely consistent with ancient shorelines.
Some oscillation ripples that commonly parallel current- ripple trends may be modifications of previously formed current ripples. Evans (1943) suggests that modification of current ripples to oscillation ripples is common under wave action where the body of water ia retreating.
Current ripples may be reliable current-trend indicators provided enough measurements are made.
Aberrant trends, aa suggested by Trow (1948) and
Pelletier (1958), are more apparent because of the low frequency of readings. Variations may be frequent, as tha Potsdam readings suggest, although many are fairly consistent with cross-bedding trends. It appears that current ripples may be useful as supporting current-trend
data when used in conjunction with cross-bedding data, but are not trustworthy when used alone. 79
Primary Currant Lineation
Primary current lineation is tha only other oriented bedding structure in the Potsdam formation. It occurs as a series of flat, weakly defined parallel ridges and grooves (Pettljohn, 1957, p. 181). Width of the ridges and grooves ranges from 2 to 4 inches and length from a few inches to several feet. This structure is formed by subequeous currents. Only six examples were observed, at localities 35, 44, and 45 (Plate II). The long axis
(current direction) is consistent with cross-bedding vector means and with most current ripples. SECONDARY STRUCTURES
Two minor secondary structures, previously undescribed from the Potsdam formation, are discussed because they resemble oriented primary structurues. They include a bedding-plane structure, best described as pseudo-ripple mark, and a type of fracturing discordant with the bedding, which looks like planar cross-bedding*
Pseudo-ripple Marks
The only known occurrence of pseudo-ripple mark in the Potsdam formation is located at Hannawe falls, ten miles south of Potsdam, New York (fig* 4, locality 6).
The structure typically consists of a series of sharp step-like ridges on a bedding plane, one surface being parallel to the bedding and the other inclined nearly at right angles to it* The parallel linear ridges thus formed extend for many feet across the exposure, resembling oscillation ripple mark (fig. 25). The width
(distance between ridges, measured parallel to the bedding) ranges from 0*5 to 2*0 inches} the width between two adjacent ridges is fairly consistent along the trend.
80 rig* 25. Pssudo-rlppls aark9 Hsnnasa Falls, Potsdaa Qusdrangls, Naa York. Visa is approxiaatsly noraal to tha dip of tha bada (tosarda tha vlaasr). Nots parsiatant linsar trends parallel to tha atrlks and at rapaatad atratigraphie intervals. Langth of stick la 14 lnchss. 82
Two examples show ths width surface inclined 6 to 0 degreea to the bedding. The depth of ridges at the surface ranges from 0.3 to 1.2 inches. The relationship of pseudo-ripple mark with bedding and sedimentary structures is shown in Figure 26.
It ie probably not fortuitous that pseudo-ripple mark occurs in a Potsdam exposure where beds are highly
inclined. This relationship suggests an origin by
secondary deformation. A number of other factors
indicate such an origin. The linear trend of the ridges
nearly always parallels the strike of the bedding. Dflost
cross-bed dip azimuths are oriented obliquely to the
trend of the ridges. Two sets of ripple marks trend
at right angles to the ridge strike and are cut by them
(Fig. 27). The inclined section rests on flat-lying
sandstones (Figs. 28 and 29), none of which shows
pseudo-ripple marks. The steep fronts of the ridges
continue into the rock as fractures. Etched cross-
sectional surfaces reveal these continuous fractures
intersecting prominent bedding at depth thus forming
repeated step-like ridges (Figs. 30 and 31). The
displacement of the lower ridges is approximately equal
to ths surface diaplacement. 83
Plane-table Map Showing Relations of Pseudo ripple Marks, Ripple Marks, and Cross-bedding in Channel of the Raquette River, Hannawa Falls, New York
STRIKE AND DIP OF POTSDAM STRATA
STRIKE OF PSEUDO- RIPPLE MARKS
DIP AZIMUTH OF INDIVIDUAL CROSS-BEDS /
DIRECTION NORMAL TO , RIPPLE MARK TREND /
TOPOGRAPHIC CONTOUR INTERVAL 5' ZERO ELEVATION ASSUMED
N ▲
V i i
2p o SCALE Fig. 26 Fig. 27. Peeudo-rlpple n r k i croaelng ripple ■arka, Hanneoa Falla9 Potadaa Quadrangle, Naa York* Vlaa la neroel to badding* Vava length of ripplo la 4 Inches. Fig* 28* Dlppino strata faultad against horizontal bsds (background), Hannaoa Falls, Potsdaa Quadrangls, Nos York* Nots pssudo- rlppls narks in Forsground psrsllsl to ths strlks* 86
Fig. 29. Dotoll of fault contact ohoon in Fig. 28. Tlltod boda contain paauda«ripplo aarks (not aheon) vhoraaa horizontal boda ahow nona. 87
rig. 30. Obli
Top Surface
s. Bedd i ng Fig. 31 * Lines of fracture
] Area of thin section (Fig 32) rig. 31. c la ■ark. 86
The displaced bedding can be matched by a comparison of grain sizes in thin section. One displaced layer (B and B't Fig. 32). is delimited at the top and bottom by a thin zone of fine quartz grains with a relatively high concentration of heavy minerals, and by a thin demarcation line of clay-size material. These demarcation lines merge at the fracture, continue along It as one line, and then separate again to delineate the top and bottom of the lower displaced layer. Unit A-A* can be similarly matched on the basis of relative amounts of iron oxide.
In addition, there tends to be a slight lineation of quartz grains parallel to the fractures.
The term pseudo-ripple mark utas coined by fflaxson and Campbell (1939) to explain plications preserved on
the vertical edge of a quartzite in contact with a mica schist in the Precambrian Vishnu schist of ths Grand
Canyon region. Originally, these authors (1934) had mistaken the structure for oscillation ripple mark.
Petrofabric analyses by Ingerson (1939) showed that the fabric of both mica and quartz in the quartzite and schist layers were related to the axis of folding.
The Potsdam structures show little identity to
those in the Vishnu, but they bear a striking resemblance
to pseudo-ripple marks described by Shrock (1940) from
the Ocoee quartzite (Precambrian?) of Tennessee. Though 89 r 2.1 Inches
■ 3> •Clay demarcation lines Relative quartz sizes x Heavy m inerals Zone of iron oxide Fig. 32 Fig. 32* Detail of thin section ecrose pseudo ripple mark fracture. 90 these structures were reported to have resulted from deformation, no description of the relation of the structure to surrounding bedding was given. The origin of the Potsdam pseudo-ripple marks is clearly poat-depoaitional, and probably occurred before final induration of the sediment. The structure may have resulted from slumping or sliding of the sand along an inclined plana that produced shear fractures nearly at right angles to the bedding. Any small irregularities on the inclined surface would be sufficient to produce shear in material in a semi-solid state with out leaving traces of such movement on the inclined surface. Probably the shear would be more easily extended through many feet of sediment if the material was soft. The orderly arrangement of trends and uniform degree of displacement was aided by the uniformity of the material through the section. The Potsdam pseudo-ripple marks are unique in that thBy occur in well-sorted orthoquartzites rather than in metamorphosed Precambrian quartzites, and at a number of stratigraphic intervals in similar sandstones rather than at a contact surface between competent and incompetent layers. This is the only occurrence known to the present writer where the relationship of the structure with primary sedimentary structures has been adequately shown. 91 Pseudo-Cross-Bedding Several examples of low-angle fracturing that reasmbla planar cross-badding vara seen in the Potsdam formation* The term psaudo-crosa-bedding is used because of this resemblance, and also because the structure has been mistaken for foreset plenee of cross-beds by previous investigators in this area. Teo examples of the structute are located in the Nicholville quadrangle (Fig* 4, area 4, one mile north of locality 7) and one in the Hammond quadrangle (Fig. 4, area 4, locality 15). The fractured unit is overlain and underlain by thick sequences of relatively horizontal beds* The fractures dip approximately 15 degrees and the planes are not tangential at the base like most Potsdam cross-bedding (Fig. 33). The complete units are much thicker than any observed cross-bedding in the local region and they are oriented opposite to local and regional cross-bedding trends. The Hammond example shows fractures that cut diagonally across smallar-scalad cross-bedded units. Close examination of all examples reveals bedding traces parallel to the horizontal layers abova and below. 92 rig. 33. Low-angle Fracturing or pseudo-cross bedding in the Potsdam sandstone, Nicholville Quadrangle, New York. Thickness of ths inclined unit is 35 inches. Ths knife is oriented in the plane of bedding of the fractured unit. 93 The fracturing la oriantad in tha same direction as ths dip of ths formation (3 to 4 degress to tha north)• Differential movement of tha upper and lower strata caused shear in the general direction of dip. PETROGRAPHY Analytical data for tha Potsdam aandstona are scarce and widely scattered. Chemical analyses were prsssntad by Colony (1919) for three localities on the northern, eastern, and southern Adirondack flanks, and by Cols (1923) for exposures at Beauharnois, Quebeo, and at Kingston and Nepean, Ontario. Heavy-mineral analyses were made by Eraser (1931) of six surface samplea at Eaglsson Corners, southwest of Ottawa, and of samples from two wells (Carleton Place and Ottawa, Ontario) where well rounded zircons and tourmalines were found at depthe of 78 feet and 1365 faet respectively. Keith (1946) compiled a list of essential and accessory minerals, with textural and chemical analyses of six selectsd exposures in parts of Leeds, Frontsnac, Lanark, and Granville Counties, Ontario (map 1946-9, Fig. 3). Recently, UUiasnet (1961) made teatural and mineralogical analyses of nine samples from Moores quadrangle, New York. 94 95 Thin-5ection Analysis Potrographic thin-ssction analyses were made in order to dstsrains general mineralogy of detrital grains* to note variations in feldspar content, and to estimate textural maturity. It was hoped that regional variations of mineralogical and textural maturity might identify positive areas at the time of deposition, A total of 300 detrital grains wera measured, using the mechanical stage, for each of 59 thin sections, minerals counted included quartz, feldspar, chart, and metamorphic quartzite. Percentages of clay (undif ferentiated), carbonate, and silica cement were estimated with tha aid of the AGI comparison charts. Opaque and heavy minerals, which wars extremely scarce, were disregarded. Krynine (1940) and Folk (1961) have devised classifications consisting of six qusrtz types based on variable extinction and on inclusions. However, there is considerable overlapping of typos based on extinction, and little agreement on types of inclusions. Inclusions described by fflackie (1896) do not entirely agree with either classification. An attempt was made to simplify the problem (as Slaver and Potter did, 1956) by claaalfying all grains that wore unstrained or mildly strained as igneous quartz; monocrystalline grains 96 showing extreme undulose extinction ss metamorphic quartz i and polycrystalline grains showing sutured and intergrown crystals as mstamorphic quartzits. Recently, Blatt and Christis (1960 and 1963), in a study of numsrous ignsous and metamorphic rocks from various locations, found that non-undulatory quartz is uncommon in plutonic igneous rocks and also in schists and gneisses* They conclude that determining provenance by undulatory extinction is valueless* It is the writer's opinion that careful sampling of possible source rocks close to immature Potsdam sandstons would have to be mads in ordsr to compare quartz types* Because of the confusion in classifying quartz types, and tha possibility that such classification is of no value, the Potsdam data have not bssn tabulated. Classification A classification by folk (1954) was selected because it allowed systematic arrangement on tha basis of mineral composition and textural maturity. Composition is plotted in figure 34 and tabulated in Table 6 (Appen dix), and maturity is tabulated in Table 7 (Appendix)* Detrital mineral components plotted are feldspar, quartz, and metamorphic rock fragments* Clay, heavy minerals, and chemical cement are ignored. The 97 COMPOSITION OF THE POTSDAM SANDSTONE RTZ ORTHOQUARTZ ITE; SURQRAYWACKE o*c rCLOSRATHIC SUMRAVWACH FELDSPATHIC IMPURE ORAYWACKE METAMORPHIC ROCK FRAGMENTS _ Fig. 34 detrital minerals are calculated to 100 per cent and then plotted on a ternary diagram (Fig. 34) with quartz-plus-chert, feldspar, and metamorphic rock fragments as the end members. Folk includes large micas with metamorphic rock fragments, a questionable procedure since such micas eould come from igneous and even sedimentary rocks. In all ths Potsdam examples, mica is absent or extremely minor (never more than 0.2 per cent); thus its presence has little effect on the plotting of composition. Estimates of texture ware mads, since grain size, sorting, clay content, and roundness are variables operating independently of minaralogical content, and reflect various energy inputs and the stability of dspositional site rather than provenance. The textural part of Folk's classification is two fold; a description of the rock on the basis of grain size, and a description of its textural maturity, which is defined by amount of clay, sorting, and rounding. The class name reflects the proportion of gravel, sand, silt, and clay. Textural maturity ranges from immature to submature, mature, and supermature. A sediment is classed as immature if it contains more than 5 per cent clay. In the other 3 classes, division is based on sorting and rounding. A sediment is submature if the size range is greater than 1 phi unit between the 16th 9-9 and 84th percentile of total grain-siza distribution, mature if the size range covers lees than 1 phi unit, and supermature if size range covers less than 1 phi unit and rounding is greater then 0,35 (Powers scale). All grains counted were measured for roundnsss using ths Powers visual scale (1953). No significant variation was found when feldspar or quartz grains were measured separately. Additional counts of the same thin sections after two days and one week (and presumably on different grains) showed a maximum of 5 per cent variation of the average value. The compositions of detrital minerals in 58 of the thin sections fall into three types, arkose (6), subarkose (15), and orthoquartzite (37, including 2 conglomeratic orthoquartzites) (Fig. 34, Table 6). One thin section is a subgraywacke. lYletamorphlc rock fragments (polycrystalline metamorphic quartzite) are present in 51 of the thin sections and decrease in amount from subgraywacke to arkose to subarkose to orthoquartzite. Feldspar is present in 52 of the thin sections; its abundance ranges from predominant (micro line) to occasional (orthoclase and perthite). Plagio- clase is extremely rare even in areas close to good plagioclase source rocks. Over 50 per cent of the feldspar is fresh in all thin sections, and some 100 thin sections show as much as 70 to 80 per cent fresh feldspar. Several chert fragments occur In two thin sections (5-14 and 5-15), Quartz overgrowths are most common as cementing agents. Carbonate Is dominant in seven thin sections but it clearly replaces pre-existing silica cement. Authigenic feldspar is present in thin sectionswith greater than 7 per cent feldspar. It occurs as over growths on ths feldspar grains. Textural differences among thin sectiona is more apparent than compoaitional differences (Table 7, Appendix). Generally, arkoses are immature, subarkoses are submature, and orthoquartzites are mature to super- mature. However, a few textural inversions occur. One of the 6 arkoses is classed as mature on the basis of sorting and a clay content of less than 5 per cent. Two of the 15 subarkoses are immature because of clay content and four are mature because of high degree of sorting. The largest variations occur among orthoquartzites. Six orthoquartzites (of 37) are immature becauae of high clay content, four of these occur in the same section (area 4, locality 7). Despite similar mineralogy and clay content, there is a very noticeable difference in rounding among the samples. 101 Regional Variations of Composition and Texture A regional plot of feldspar content uias made in order to see urhere feldspathic rocks grade into purB orthoquartzites (Fig. 35). Most samples come from with in 5 to 15 feet of the base of the formation. The largest feldspar concentration occurs along the south eastern, eastern, and northeastern borders of the Adirondacks, and feldspar decreases away from them. Secondary concentrations occur on the Frontenac axis and locally in the vicinity of Montreal. Noteworthy is the absence or extreme scarcity of feldspar adjacent to the north-central Adirondack border, at exposures adjacent to the Canadian Shield, and in the St. Lawrence Lowland. Comparing this distribution with cross-bedding studies, it appears that the eastern Adirondacks and the northward-extending Qeauharnois anticline were major sources of sediment especially during early stages of Potsdam deposition. This agrees with the cross-bedding measurements which indicate southeast and east trends off the eastern Adirondacks and southeast trends off the Beauharnois anticline. The even disposition of contours along the eastern border of the Adirondacks suggests effects of wave erosion evenly concentrated along the shoreline. Northward-directed fluvial transport of 102 30 10 Contour interval 10°A 3 0 - Fig. 35 FELDSPAR CONTENT OF THE POTSDAM SANDSTONE 103 sediment may account for part of the northeastern loop of the contour pattern. This region contains several subgraywackes and some red shale (according to U/iesnet, 1961). If fluvial transport did occur, the sediment must have besn diverted and redistributed quickly to the east and southeast by marine currents as the cross beds suggest. After thB Beauharnoia anticline was crossed and marine transgression proceeded westward in the subsiding basin, both the anticline and the Adirondacks ceased to be the major source of Potsdam sediment. The composition al maturity of sediments on the periphery of the St. Lawrence Lowland suggests a different and much more distant source. Cross-beds show currents to be from the north. A southerly cross-bed trend follows the trend of the zero feldspar contour on the eastern side of the St. Lawrence Lowland and both trends bend slightly westward where they approach the Adirondacks. The low feldspar content along the north-central Adirondacks may be a result of reworking of sediments over a long period of time or perhaps a lack of feldspathic source rocks. The latter is suggested by the low feldspar content of the Nicholville conglomerate that is locally present in the north-central Adirondacks. The northward- trending large-scaled festoon cross-beds of the Nichol ville conglomerate must have been produced by energetic 104 streams off a relatively high source and the paucity of feldspar probably mas a result of a lack of feldspar in the source rocks. The higher feldspar concentrations off the north western Adirondacks and the Frontenac axis are the result of direct erosion of underlying Precambrian knobs during late stages of the marine transgression. Southerly and southeasterly currents in this region indicates the major source from the north and the wrap-around effect of cross-bedding emphasizes the positive nature of the northwestern Adirondacks at this time. The re-entrant between the Frontenac axis and the northwestern Adirondacks suggests a late-stage crossing of the axis. Sandstones of the St. Lawrence Lowland and along the north-central Adirondack border show the highest percentage of non-undulatory quartz (generally more than 90 per cent) . Although a distinction of quartz types may not be useful for provenance studies, predominance of non-undulatory quartz may suggest a high degree of maturity. Blatt and Christie (1963) show thst meta- quartzite and undulatory quartz are selectively destroyed by mechanical abrasion. The high concentration of non-undulatory quartz in the St. Lawrence Lowland and the north-central Adirondack flank suggest multi-cycle 105 sands that were abraded for a long time under marine conditions and were probably derived from a source other than the Adirondacks. A regional plot of roundness (fig. 36) shows that the feldspar content has a similar pattern. There is some overlap of medium to high rounding values in areas where rocks contain 10 per cent or more feldspar. Heavy-mineral Analysis Analyses of transparent heavy minerals were made on two widely separate sections of the Potsdam in order to determine whether there is any similarity of mineral species, and especially any variations in types of tourmaline, percentage of overgrowths, and roundness, through a vertical section. The eastern section is 200 feet of sandstone (predominantly subarkose) at Cadyvllle, Oannemora quadrangle, New York. Heavy-mineral separates were made at 20-foot intervals. The western section is a composite section representing 125 feet of sandstone at two adjacent localities. This section represents a nearly complete section of the Potsdam, as the 1owest sample is estimated to be 10 feet above Precambrian rocks. Heavy-mineral separates were made at approximately 9-foot intervals. 106 1-Lowest value 5-Highest value Fig. 36 2^ 3' VAR I AT I ON IN DEGREE OF ROUNDNESS IN THE POTSDAM SANDSTONE A. 107 Three hundred grains per section were counted. Grain size ranges from 0.062 to 0.50 mm. minerals include zircon, tourmaline, rutile, apatite, garnet, biotite, muscovite, and questionable sillimanite. Tourmaline was divided into igneous and metamorphic types based upon Krynine's criteria (1940). All tourmaline grains showing authigenic overgrowths were noted. Degree of roundness was divided into two groups; grains less than 0.6 (based on Krumbein's roundness scale (1941)) were classed as angular, those greater than 0.6 were classed as round. A zircon-tourmaline- rutile (ZTR) index was computed for each sample. The analyses are presented in Tables 6 and 9 (Appendix). Zircon and tourmaline predominate in both sections. Occasionally, tourmaline is greater than zircon (e.g., section C-4 in the subarkose facies; sections AB-2, 6, 12, H-l and 2 in the orthoquartzite facies). This periodic change is simply a difference in hydraulic behavior and sorting at various intervals. Rutile seems to be consistently low in both sections. The sections display more notable differences than similarities. The tourmaline in the orthoquartzite section shows a much greater percentage of authigenic overgrowths, better rounding of detrital tourmalines, and a higher ZTR index. Periodic influx of new material is evident in the subarkose facies, as shown by accessory 10 B heavy minerals, uihereas there is a consistent decrease of such accessories from bottom to top in the ortho quartzite section, ll/here there is a predominant influx of accessories, there is a decrease in igneous tourmaline (e.g., section C-10), and a noticeable lowering of tourmaline rounding (e.g., sectionsC-1 and C-10). Krynine (1946) has suggested that authigenic tourmaline is sedimentary and was formed at the bottom of the sea at the samB time as thB including sediment. If this is true, then both sections are marine. The large percentage of tourmaline overgrowths in the western composite section reflects perhaps slower accumulation of sediment and therefore, longer intervals of time for overgrowths to develop. A marine origin is assumed for the eastern section on the basis that overgrowths do occur (regardless of amount), but the low percentage probably reflects rapid accumulation. Periodic influx of greater amounts of other accessory heavy minerals in this section suggest periodic uplift in the source area* Differences in the degree of roundnees reflect only the difference in abrasion history at the site of deposition. CONCLUSIONS The purpose of this study ives to investigate the paleocurrent system of the Potsdam sandstone so that suggestions could be made about its source and dispersal. Primary bedding-plane structures were measured for orientation, and they included cross-bedding, current ripple marks, oscillation ripple marks, and primary current lineation. Cross-bed distributions were plotted by a variety of methods including rose diagrams, vector means, and a moving average. Ripple marks and primary current lineation were plotted separately and compared with cross-bed vector means. Thin-section analyses were made to determine the mineralogical and textural maturity of the sandstone, and distribution plots were drawn of feldspar content and average roundneas. Heavy-mineral analyses were made through two vertical sections in order to determine types of heavy minerals, and especially variations in types of tourmalines, percent age of overgrowths, and roundness. 109 110 History of Deposition The presence of fossils in approximately the upper half of the Potsdam formation, and the upward gradation of the Potsdam into dolomite, have been the basis for assigning a marine origin to the formation. Other features suggesting a marine origin are as follows! 1, Lack of intercalated muds throughout the Potsdam. 2, Progressive increase upward in thickness and directional stability of cross-beds in the Frontenac axis region as a protected embayment changed to a more open environment, 3, Persistence of current trends directed toward the Adirondack high through arkose and some conglomerates, and a general lack of outpouring of sediments from the Adirondacks. 4, High textural and mineralogical maturity of most sediments in the St. Lawrence Lowland. 5, The following features in rocks stratigraphic- ally low in the Potsdam sandstone (east and northeast m. Adirondack flanks)i a. Oscillation ripple marks close to th B Precam- brian basement rocks, b. Herringbone structures similar to those in stratigraphically higher sections. I l l c. Authigenic tourmaline overgrowths. d. Frequent mixing of cross-bed types and lack of consistent regional variation of cross-bedding thicknesses, conditions that are similar to those stratigraphically higher. e. Rapid decrease in feldspar content and increase in average roundness. These suggest winnowing action under marine conditions. Evenness of the contour patterns of both feldspar content and roundness is best explained by nearshore wave action acting consistently along the uthole stretch of the eastern Adirondacks. The extent of marine onlap onto the Adirondack surface was probably close to the position of the contour showing the highest feldspar content. The zero per cent feldspar contour roughly outlines the north-central Adirondack border. One outcrop just south of the zero feldspar line shows the Nicholville conglomerate (cross-beds trending north) interfingering with mature sediments tnat came from the north. There is no evidence of a southward extension of the mature sediments over the conglomerate. The Adirondack mountains, Frontenac axis, Beauharnois anticline, and Canadian Shield all contributed material to the Potadam sandstone. The northeastern Adirondacks, 112 ths Beauharnois anticline, and tha Canadian Shield uiere the dominant sources, other areas being local contribu tors. Several phases of the depositional history of the Potsdam sandstone are recognized, on the basis of the influence and location of dominant sources. 1. The eastern Adirondacks and the Beauharnois anticline were the major source areas during the early phase of depositional history. They produced eastward and southeastward currents moving away from the positive regions. The northeastern Adirondack produced immature subarkoses, subgraywackes, and red shales (lUiesnet, 1961) that may have been partly fluvial in origin but were quickly dispersed by marine currents flowing southeasterly. Active uplifting occurred in the northeastern Adirondacks as suggested by extended arcs of high feldspar content and low average roundhess values. Periodic uplift is indicated by recurring influxes of accessory heavy minerals and metamorphic rock fragments. Vertical movements were sufficient to create enough erosive activity to produce a predominance of fresh feldspar (mlcrocline) over weathered feldspar. A pronounced predominance of biotite over muscovite in the heavy-mineral fraction also favors erosion rates that overbalance rates of weathering. 113 2. A second depositional phase occurred when the Beauharnois anticline was crossed by wastward migrating seas into the St. Lawrence Lowland. The crossing may have occurred near the present junction of the St. Lawrence and Ottawa Rivers, where several notable cross-bed reversals occur. Rocks in the Canadian Shield now become the dominant source of the Potsdam material. Subsidence was sufficient so that southward currents were confined to the western side of the Beauharnois anticline. These currents were turned southwestward when they abuttBd against the northern Adirondacks. Southerly currents moved off the Shield in the vicinity of Ottawa and were diverted slightly south- westward at the Frontenac axis. The pattern diverted more to the southwest when currents abutted against the northwestern Adirondacks. A re-entrant developed between the northwestern Adirondacks and the Frontenac axis and currents were channeled through it. Both the Frontenac axis and the northwestern Adirondacks were local sources for feldspar, mainly a result of direct erosion of underlying basement rocks by transgressing seas. The bulk of the sediment on and near these areas, however, was supermature and was derived from more distant sources to the north. The progressive increase of cross-bed frequency and thickness upward in the section, and the presence of 114 many dip-azimuth deviations, indicate local marine embayments onto several stable Prscambrian highs. The high textural maturity, dominance of non-undulatory quartz, and high percentage of tourmaline overgrowths throughout a vertical section, indicate a long abrasion history on an extremely stable shelf. Lvaluacion of Procedures 1, A plot of vector means provides the best method of illustrating a regional cross-bedding pattern. Its value lies in giving both a resultant or average current direction for all cross-beds at each locality and a measure of vector strength, which shows the consistency or amount of dispersal of the resultant. A cursory glance gives sense of dispersal direction and the relative stability of that trend. Computing a vector summation by looking up all values of sine and cosine in standard tables is a tedious task and one that is subject to numerous repetitive erros. Methods suggested by Pincus (1956) are also relatively slow. A simple computer program, based on formulas used by Pincus (1956) and Curray (1956), is suggested in order to speed up the project. 115 It is estimated that at least five weeks of hard labor was condensed Into 1.5 minutes of computer time with results that were without error. Several cross-bed locations should be computed by long hand in order to see if the program is correctly set up. 2. A moving average of cross-bedding is helpful In that it tends to smooth out irregularities and to bring out some shifts in the general trends that may not be apparent in a plot of vector means. For example, the separation of east-trending currents off the Beauharnois anticline from southerly currents off the Canadian Shield and running parallel to the axis is best shown on the moving-average diagram. Summing of vector resultants for the moving average Involves identical procedures to those employed in computing vector means. 3. A plot of circular histograms is helpful if it is desirable to show effects of current reversals, deviations from the main current trend, or bimodal distributions. Generally, a simple location description of the concentration of such abberant deviations should suffice. A local analysis, however, proved useful in showing the topographic control of Potsdam cross-beds in the Frontenac axis area. 116 Since the computer has to know what the azimuth of the cross-bed Is before It looks up sine and cosine, it is a simple initial step to design the program so that the computer automatically groups the azimuths into 10-degree intervals (or any intervals), counts them and computes percentages of total azimuths for each 10.degree interval* 4. ^The computer program is designed to make a vector analysis on any oriented sedimentary structure where either up-current or down-current direction can be determined. Additions can be made to the program following suggestions by Curray (1956, p. 119), which would render the computer program effective for any oriented feature such as drag marks, grains fabric, and fossil lineations. 5. Cross-bed types are of no value for indicating environments of deposition. Potsdam data show frequent alternation of types in many sections. 6. A distribution plot of cross-bed thickness is important if fluvial environments are suspected. Lack of thickness variation in the Potsdam cross-beds suggests that they were formed under remarkably stable and uniform conditions. 7. Establishing vertical consistency of cross-bed vector means may not be necessary. All studies to date show a generally consistent directional pattern no matter 117 where one is in the section. It appears that once the region was flooded by transgressing seas and the direction of current flow became established, there was little variation from this initial trend throughout the time of deposition of the formation. 8. Current-ripple trends are generally parallel to cross-bed trends; where a large deviation occurs, it is consistent with a high dispersion for the cross-bedding. The frequency of current-ripple measurements is too low to be of great importance when they alone are recorded, and this seems to be true in other formations also. Since aberrant current-ripple trends are known to exist in other formations, the Potsdam trends were plotted individually in order to show similarity or dissimilarity of the pattern with respect to cross-beds. Current ripples that parallel cross-bedding trends can be included with the cross-bedding measurements at each exposure. If notable abnormal orientations occur consistently, then current ripple data must be plotted separately. 9. Aside from the environmental importance of oscillation ripple marks and greater frequency toward Precambrian highs, they show no consistent orientation of trends parallel to the shoreline. 10. If Krynine's work (1946) is valid, the presence of authigenic tourmaline overgrowths should suffice to determine marine origin of sediments. Tabulating xia percentage differences may be advantageous in establish ing the relative rate of deposition or the length of time available for authlgenic tourmaline to grout. 11* Tourmalines are better rounded in the ortho- quartzite section than in the subarkose section. Tourmaline roundness provides a good abrasion index and should vary regionally. Geographic variation of tourmaline roundness has been used effectively by Rittenhouse (1949) and Slever and Potter (1956). 12. A distribution plot of a mineral leas stable than quartz may be useful in establishing source areas. Feldspar mas used in this study because of its avail ability in source rocks. The consistency of the pattern may also be useful* Contours of feldspar content are evenly distributed and the content decreases rapidly in a short distance from the Precambrlan highs, a result of long abrasion under near-shore marine conditions. Care must be taken in analyzing dispersion of less stable minerals far from a source because of the possibility of dilution from other sources and the differences of hydraulic behavior of various minerals. 13. A distribution plot of average roundness values mas useful for distinguishing sources for the Potsdam, although decreasing values of feldspar content geo graphically followed the steady decrease in roundness. 119 Roundness helped differentiate source of the material on the northern Adirondack border when the distinction could not be made on feldspar content. Rounding values may be of great importance because they can be determined on quartz grains which are alu/ays available. Again the consistency of contour patterns or the lack of it may be useful in determining the influence of various sources and possibly the conditions of deposition. APPENDIX 121 Table 5 Cross-bedding Statistics Locality Number of Vector Vector Standard Number Readings Resultant magnitude Deviation SECTION 1 1 9 223.0 70 .55 67.49 2 10 155.60 09.16 28.74 3 9 167 .5 73.09 54.78 4 11 202.1 74.29 52.95 SECTION 2 1 16 135.1 03.91 35.47 2 9 131.6 01.69 38.52 3 25 91.4 67.99 54.31 4 22 139.5 72.26 59.81 5 0 102.0 63.53 59.18 SECTION 3 1 0 136.3 95.91 17.59 2 10 133.6 77.87 47.75 3 0 157.1 91.51 25.54 4 12 132.3 60.75 53.57 5 10 115.7 09.40 27.51 , 6 12 06.0 71.50 51.23 7 25 136.1 72.35 46.07 0 11 129,,7 49.93 72.67 t. 9 17 147.1 70.95 40.79 10 15 100.7 06.91 31.19 122 Table 5 - Continued Locality Number of Vector Vector Standard Number Readings Resultant Magnitude Deviation 11 10 96.92 73.83 52.50 12 14 325.8 18.53 99.40 13 14 84.74 85.10 33.83 14 25 141.7 84.54 37.36 15 16 96.18 58.50 67.23 16 23 133.2 70.34 51.41 17 7 80.63 83.92 36.15 18 16 115.4 95.91 34.68 19 11 126.0 87.94 30.28 20 28 117.1 51.53 63.52 21 14 104.2 66.33 67.30 22 7 162.2 94.07 21.47 23 48 108.9 86.52 32.04 24 32 129.8 06.52 31.39 25 12 287.4 42.14 82.49 26 10 115.6 53.29 81.77 27 9 127.8 68.59 60.87 28 6 156.8 94.09 21.79 SECTION 4 1 26 118.2 60.53 72.54 2 5 292.5 97.66 13.B8 3 10 216.6 42.82 71.36 4 8 244.7 57.19 71.40 123 Table 5 - Continued Locality Number of Vector Vector Standard Number Readings Resultant magnitude Deviation 5 9 125.2 83.50 36.44 6 21 195.6 00.35 42.28 7 37 311.5 21.01 94.51 8 38 210.6 91.26 24.72 9 11 197.9 95.28 18.60 SECTION 5 1 26 217.6 87.05 36.97 2 31 262.4 71.43 51.09 3 18 241.8 44.19 80.52 4 23 215.6 66.53 59,24 5 18 197.0 97.17 14.09 5 13 229.6 81.57 47.55 7 29 228.1 75.20 50.31 8 24 235.8 94.47 19.70 9 30 257.9 62.13 59.53 10 9 245.6 95.26 10.84 11 13 245.8 76.25 57.10 12 16 222.9 88.06 29,68 13 13 250.3 79.95 42.27 14 15 227.1 69.07 52.55 15 44 251.7 47.32 71.29 16 64 254.7 80.01 40.72 17 30 222.2 69.81 58.01 124 Table 5 - Continued Local!ty Number of Vector Vector Standard Number Readings Resultant magnitude Deviation IS 17 225.9 62.55 59.26 19 12 248.4 97.71 12.85 20 10 178.9 94.91 19.44 21 43 179.2 71.54 58.46 22 13 162.0 74.86 49.91 23 14 179.9 70.31 55.95 24 9 171.4 50.14 73.64 25 14 190.2 95.03 18.92 26 6 152.7 94.27 21.49 27 14 189.7 90.28 26.69 28 8 9.4 26.57 84.36 29 18 182.6 69.19 58.66 30 16 200.0 79.32 43.13 SECTION 6 1 38 196.1 87.43 31.59 2 10 183.6 75.53 60.37 3 34 201.1 75.70 52.48 4 15 202.3 77.79 54.03 5 12 203.9 80.11 43.96 6 23 197.9 76.75 45.51 7 20 194.9 93.79 20.98 8 15 209.4 93.97 20.91 9 17 204.2 74.06 46.89 Table 5 - Continued umber of Vector Vector eadinga Resultant magnitude 10 12 209.9 70.38 11 B 218.9 91.67 12 13 67.0 53.49 13 39 239.7 91.34 14 11 220.4 89.56 15 26 180.5 53.97 16 16 236.1 91.49 17 37 180.2 77.82 19 38 209.9 86.08 19 26 219.0 92.63 20 11 84.9 65.65 21 28 24.5 71.28 22 46 220.9 94.69 23 57 248.2 81.49 24 23 226.2 67.99 25 29 215.7 57.19 26 50 222.9 56.59 27 24 216.2 95.23 29 26 303.4 6.72 29 15 213.3 76.57 30 14 228.1 97.11 31 12 35.9 21.90 32 12 194.8 95.27 126 Table 5 - Continued L ocali ty Number of Vector Vector Standard Number Readings Resultent fflagni tude Deviation 33 9 334.9 96.05 17.20 34 14 160.9 96.39 16.05 35 11 156.6 75.49 53.65 36 35 152.5 90.31 26.07 37 9 210.5 73.74 62.21 30 12 206.0 66.50 61.89 SECTION 7 1 16 169.6 95.73 17.41 2 14 138.8 57.29 69.24 3 20 160.2 56.85 58.60 4 9 135.4 92.26 24.23 5 11 187.8 92.74 23.39 6 9 202.5 92.89 23.21 7 21 145.1 84.98 34.21 SECTION B 1 16 128.8 51.35 64.00 2 25 111.2 94.70 19.32 3 26 33.9 07.85 29.69 4 15 70.5 89.51 27.82 5 11 136.7 93.02 22.71 6 10 166.2 79.20 40.56 7 11 102.2 37.79 74.33 8 10 154.9 82.79 36.29 127 Table 5 - Continued Locality Number of Vector Vector Standard Number Readings Resultant magnitude Deviation 9 11 24.7 25.00 102.24 10 10 135.5 71.43 48.62 WESTPORT QUADRANGLE, ONTARIO, CANADA 1 11 123.7 28.16 79.40 2 16 236.1 91.49 24.79 3 15 192.4 04.02 40.82 4 11 162.2 93.12 22.57 5 26 109.6 74.26 48.64 6 16 204.0 95.13 18.75 7 22 214.2 79.99 47.60 8 10 228.5 91.47 25.41 9 16 213.2 94.64 19.70 H r-t CD CM 10 24 216.2 95.29 e 11 11 220 .2 96.34 16.37 12 14 98.7 19.76 93.28 13 13 227.9 96.97 14.76 14 26 303.4 6.72 93.26 15 12 224.8 56.23 69.60 16 10 213.8 57.47 78.29 17 9 224.1 93.74 21.67 18 10 193.0 27.06 84.60 19 13 216.9 94.16 20.54 128 Table 5 - Continued Locality Number of Vector Vector Standard Number Readings Resultant Magnitude Deviation 20 10 255.3 40.45 92.49 21 12 194.8 95.27 18.52 22 9 334.9 96.05 17.20 23 11 156.6 75.49 53.65 24 9 218.5 73.74 62.21 25 12 35.9 21.90 89.19 26 8 54.4 96.10 17.24 27 5 69.9 98.94 9.35 28 15 347.7 81.81 37.02 29 11 84.8 65.65 52.42 30 27 214.7 94.12 20.30 31 19 229.5 97.38 13.54 32 57 248.2 81.46 44.B1 33 14 228.1 97.11 14.40 34 8 212.9 93.99 21.54 35 7 213.9 56.66 63.42 36 35 152.5 90.31 26.07 37 14 168.9 96.39 16.05 38 12 206.6 66.58 61.89 Table 6 Petrographic Composition (in per cent) of Potsdam Sandstone LOCATION Total Detrital 0 ther Computed detri- (refer to Tig. 4) authigenic Detrital rock frag Clay au thigenic tal quartz and detrital feldspar ments and * Feldspar (100% - % Feld. ♦ Area Locality quartz micas ** Calcite rcjck fragments) 1 1 63.4 31.2 2.7 1.2 2.0 * 66.3 1 3 59.4 12.1 0.6 0 19.0 ** 87.4 1 4 95.2 4.6 0.2 0 0 95.2 1 5 50.0 41 .0 1.3 7.0 1.0 * 57.7 2 1 78.1 19.5 1.4 0.5 0.5 * 79.1 2 1 04.2 14.3 0.6 0.7 0.2 * 85.1 2 4 02.0 10.5 7.5 0 0 82.0 2 4 09.5 6.3 2.1 2.2 0 91.7 2 10 miles 79.4 19.5 0.1 0.5 0.5 * 80.4 2 North of 02.4 16.3 0.1 0.7 0.5 * 03.6 2 Locality 5 88.5 10.3 0 1.1 0.1 * 89.7 3 1 76.0 10.1 13.0 0.9 0 76.1 3 a 82.3 14.6 0.6 2.3 0.2 * 04.0 3 16 61.9 30.6 0.9 4.6 2.0 * 68.5 3 20 56.8 33.5 0.7 6.8 2.2 * 65.9 3 23 69.9 20.0 1.0 6.3 1.0 * 77.4 3 23 01.0 13.2 0.9 4.2 0.5 * 85.9 4 3 97.5 0.5 1.0 1.0 0 98.5 4 4 86.7 0 3.3 10.0 0 96.7 4 5 90.1 0 0.9 9.0 0 99.1 4 6 96.8 0 1.2 3.0 0 98.9 4 7 08.9 - 0.2 0 11.0 0 99.0 h-* N> UD T abl e 6 - Continued LOCATION Total Detrital Other Computed detri- (refer to Fig. 4) authigenic Detrital rock frag Clay authigenic tal quartz and detrital Feldspar ments and * Feldspar (100% - % Feld. ♦ Area Locality quartz micas ** Calcite rock fragments) 4 7 87.6 0.2 0.2 12.0 0 99.6 4 7 92.0 0.3 0 8.0 0 99.6 4 7 87.9 0.1 0.2 12.0 0 99.7 4 7 95.0 0.2 0 4.9 0 99.7 4 9 76.8 1.2 1.5 0.5 20.0 ** 97.3 5 4 98.1 0.4 0 1.5 0 99.6 5 4 98.5 0 0.5 1.0 0 99.5 5 5 97.4 0.4 1.2 1.0 0 98.4 5 5 97.8 0.2 1.0 0.5 0.5 ** 98.8 5 6 98.1 0.2 1.3 0.5 0 99.5 5 9 98.5 0 0.8 1.0 0 99.2 5 11 96.5 0 0.5 3.0 0 99.5 5 11 92.4 0.3 0 0 7.0 ** 99.4 ( ,3 chert) 5 15 95.6 0.5 0.5 3.0 0 98.6 (.4 chert) 5 15 98.2 0.3 1.4 0.5 0 98.7 5 16 79.2 13.5 5.8 1.0 0.5 * 80.7 5 16 96.5 0.5 0 3.0 0 99.5 5 21 97.0 2.0 0.5 0.5 0 97.3 5 22 96.9 1.5 1.3 0.3 0 97.2 5 22 87.1 3.1 0 0.8 12.0 ** 96.9 5 23 63.9 4.6 0.5 1.0 30.0 ** 94.9 6 0 99.5 0 0.5 0 0 99.5 130 6 12 86.6 7.5 4.5 2.0 0 88 .0 6 22 98.5 0.2 0.3 1.0 0 99.5 Table 6 - Continued LOCATION Total Detrital Other Computed detri (refer to Fig. 4) authigenic Detrital rock frag Clay authigenic tal quartz and detrital f eldspar ments and * Feldspar [100% - % Feld. ■ Area Locality quartz micas ** Calcite rock fragments) 6 31 63.1 14.5 1.8 20.0 0.6 * 83.7 6 31 98.1 0.5 0.4 1.0 0 99.1 6 33 45.8 43.2 1.0 10.0 0 65.8 5 33 57.5 31.5 1.0 10.0 0 67.5 6 36 94.9 0.9 1.0 3.2 0 98.1 7 2 95.0 2.5 1.5 1.0 0 96.0 7 3 99.1 0.2 0.4 0.5 0 99.4 7 4 66.8 2.5 0.2 0.5 30.0 ** 97.3 8 1 96.9 2.0 0.8 0.3 0 97.2 8 7 68.7 7.5 2.6 1.0 20.0 ** 89.9 0.2 * 8 8 99.5 0 0.2 0.3 0 99.8 8 8 97 .9 0.3 0.5 1.5 0 99.2 131 Tabl Textural Maturity of Potsdam Sandstone LOCATION T extural (refer to Fig. 4) Roun Rock Name dn0ss Description Maturity Area Locality 1 1 1 •6 Sandstone Immature Arkose 1 3 2 .1 " Submature Subarkose 1 4 3 .2 " Mature Orthoquartrite 1 5 1 .0 M Immature Arkose 2 1 1 Submature Subarkose 2 1 1 Submature Subarkose 2 4 1 Submature Subarkose 2 4 2 Mature Subarkose 2 10 miles 2 Submature Subarkose 2 North of 2 Submature Subarkose 2 Locality 5 2 Mature Subarkose 3 1 2 Submature Subgrayvacks 3 8 2 Immature Subarkose 3 16 2 Mature Arkose 3 20 1 Immature Arkose 3 23 2 Immature Subarkose 3 23 3 Mature Subarkose 3 3 Supermature Orthoquartzite 4 4 Immature Orthoquartzite 5 4 .0 M Immature Orthoquartzite 6 4 .5 " Supermature Orthoquartzite 7 3 .9 " Immature Orthoquartzite 7 2.0 Slightly con- Immature Conglomeratic orthoquartzite 7 2 .7 glomeratic ss. Immature Conglomeratic orthoquartzite 7 3 .6 Sandstone Immature Orthoquartzite Table 7 Continued LOCATION Size Textural (ref er to Fig. 4) Roundness Rock Name Description maturity Area Locality 4 7 3.9 Sandstone Supermature Orthoquartzite 4 9 4.5 N Supermature Orthoquartzite 5 4 5.0 N Supermature Orthoquartzite 5 4 5.2 N Supermature Orthoquartzite 5 5 5.0 N mature Orthoquartzite 5 5 5.6 ft Supermature Orthoquartzite 5 6 4.0 it mature Orthoquartzite 5 9 5.0 H Supermature Orthoquartzite 5 11 5.1 ft Supermature Orthoquartzite 5 11 5.0 II Supermature Orthoquartzite 5 15 4.2 H Supermature Orthoquartzite 5 15 3.5 M Supermature Orthoquartzite 5 16 2.0 M Submature Subarkose 5 16 4.0 H Supermature Orthoquartzite 5 21 4.0 M mature Orthoquartzite 5 22 5.4 H Supermature Orthoquartzite 5 22 5.0 H Supermature Orthoquartzite 5 23 3.1 N mature Orthoquartzite 6 6 4.5 It Supermature Orthoquartzite 6 12 3.5 ft mature Subarkose 6 22 4.2 H Supermature Orthoquartzite 6 31 2.9 ft Immature Subarkose 6 31 4.0 tf Supermature Orthoquartzite 6 33 1.5 It Immature Arkose 6 33 1.0 It Immature Arkose 6 36 3.0 It Supermature Orthoquartzite 7 2 3.5 If Supermature Orthoquartzite 7 3 5.0 H Supermature Orthoquartzite 7 4 4.5 H Supermature Orthoquartzite Table 7 Continued LOCATION Size Textural (refer to Fig. 4) Roundness Rock Name Description maturity Area Locality 8 1 5.0 Sandstone Supermature Orthoquartzite 8 7 2.5 M Submature Subarkose 8 8 5.8 M 5upermature Orthoquartzite 8 8 3.5 « mature Orthoquartzite Table 8 Heavy-mineral Analyses (in per cent) of the Orthoquartzite Facies, Alexandria Bay and Hammond Quadrangles, New York (Vertical separation of each analysis approximately B feet) ZIRCON TOUR- RUTILE OTHERS TOURMALINE______Z T R Thin 71AL INE Over 0.6 Index Ign eous fflet. Sect. growths roundness Number T op H-2 41.2 56.8 0.98 0.98 51.B 48.2 86.2 86.2 98.9 H-l 48.1 49.1 1.47 0.98 67.3 32.7 76.0 65.6 98.6 AB-12 42.1 49.0 2.00 8.01 69.5 30.5 48.7 61.8 92.1 AB-11 61.5 43.7 0.66 0.66 73.7 26.3 37.9 83.0 98.3 AB-10 57.9 40.7 0.49 0.49 79.2 20.8 58.2 75.7 98.0 AB-9 61.0 37 .8 0.98 0.39 62.4 37.6 68.7 70.2 98.2 AB-9 59.2 38 .7 1.64 0.53 59.7 40.3 64.7 69.6 97.6 AB-7 56.8 41.6 0.99 0.49 51.3 48.7 79.8 67.2 9B.B AB-6 27.9 67.8 2.32 1.16 61.0 39.0 44.1 77.5 98.0 AB-5 63.6 32.4 2.78 1.12 74.2 25.8 46.6 76.8 97.5 A8-4 57.6 39.4 1.52 1.52 89.6 10.4 7.7 70.0 97.9 AB-3 63.4 34.2 1.42 1.06 74.4 25.6 30.5 70.6 99.0 AB-2 45.6 50 .4 1.40 2.50 74.5 25.5 68 .2 48.2 97.7 A9-1 72.3 23.8 1.44 2.56 83.4 16.6 69.9 59.2 97.4 9ot tom Table 9 Heavy-mineral Analyses (in per cent) of the Subarkose Facies, Dannemora Quadrangle, Cadyville, Neui York (Vertical separation of each analysis approximately 20 feet) ZIRCON TOUR- RUTILE OTHERS TOURMALINE Z T R Thin MALINE Over 0.6 I ndex Igneous Met. Sect* growths roundness Number T op C-10 50.0 35.10 0.58 13.60 58.4 41.6 2.80 63.0 06.6 C-9 59.2 37.40 0.53 2.87 73.1 26.9 2.40 76.2 97,4 C-B 61.4 35.50 1.75 1.62 76.4 23.6 2.51 82.1 90.2 C-7 63.0 33.90 1.43 1.60 65.0 35.0 7.94 74.0 97.0 C-6 54.3 40.50 0.00 4.39 01.1 18.9 5.16 74.0 95.5 C-5 51.3 46.20 0.20 2.23 79.1 20.9 5.90 71.5 96.0 C-4 48.1 49.20 0.38 3.01 02.4 17.6 6.10 73.8 97.0 C-3 52.0 44.10 0.31 2.70 02.5 17.5 7.75 63.5 97.2 C-2 67.4 28.60 0.90 3.30 55.9 44.1 10.63 75.8 95.0 C-l 64.5 25.20 0.69 9.53 70.4 29.6 15.50 69.8 90.4 1 Bottom BIBLIOGRAPHY Ailing, H. L., 1919, Geology of the Lake Clear region (parts of St. Regis and Saranac quadrangles)i N.Y. State ITIus. Bull. 207-20B, p. 111-145. Bagnold, R. A., 1942, The physics of blown sand and dunesi Hi. morrow and Company, Inc., New York, 265 p . Bausch van Bertsbergh, Jan Ui•, 1940, Richtungen der sedimentation in der Rheinischen geosynklinet Geologische Rundschau, v. 31, p. 328-364. Blatt, H., and Christie, J. m., 1960, Undulatory extinction in quartz of igneous and metamorphic rocks and its significance in provenance studies of sedimentary rocks (Abs.)i Geol* Soc. America Bull, v. 71, p. 1828. --, 1963, Undulatory extinction in quartz of igneous and metamorphic rocks and its significance in provenance studies of sedimentary rockst Jour. Sed. Petrology, v. 33, no, 3, p. 559-579. Brainerd, £., and Seely, H. m., 1890, The Calciferous formation in the Champlain Valleyi Amer. mus. Nat. Hist. Bull., v. 3, p. 1-23. Brett, G., 1955, Cross-bedding in the Baraboo quartzite of U/isconsim Jour. Geology, v. 63, p. 143-148. Briggs, G«, 1963, Paleocurrent study of the Brazos River sandstone member of the Garner formation, Palo Pinto County, Texasi Jour. Sed Petrology, v. 33, no. 1, p. 87-104. Buddington, A. F., 1934, Geology and mineral Resources of the Hammond Antwerp and Lowville quadrangles} with a chapter on the Paleozoic rocks of the Lowville quadrangle, by Rudolf Ruedemanm N.Y. State ffius. Bull. 296, 251 p. 137 130 Buddington, A. F., and UJhitcomb, L., 1941, Geology of the Willsboro quadrangle, New Yorkt N.Y. State lYlus. Bull. 325, 137 p. Chadwick, G. H., 1915, Post-Ordovician deformation in the St. Lawrence Valley, New York (Abs.)> Geol. Soc. America Bull., v. 26, p. 289-291. --, 1920, The Paleozoic rocks of the Canton quadranglet N.Y. State mus. Bull. 217-218, p. 1-60. Clarke, J. ffl., 1910, Sixth Report of the Oirector of the Science Division including the 63rd Report of the State museum, the 29th Report of the State Geolo gist, and the Report of the State Paleontologist for 1909* N.Y. State mus. Bull. 140, p. 11-12. Clarke, J. ID., and Schuchert, C., 1899, The nomenclature of the New York series of geological formationsi Science, N.S., v. 10, p. 874-878. Clarke, Thomas H«, 1952, Laval and Lachine map areast Quebec Dept, of mines, Geol. Surveys Branch, Geol. Rept. 46, 159 p. Colony, R. J., 1919, High-grade silica materials for glass, refractories and abrasivesi N.Y. State mus. Bull. 203-204, 31 p. Cressey, G. B., 1928, The Indiana sand dunes and shore line of the Lake michigan Basin: Geol. Soc. Chicago, Bull. 8, p. 3. Curray, J. R., 1956, Analysis of two-dimensional orien tation data: Jour. Geology, v. 64, p. 117-131. Cushing, H. P., 1894, Preliminary report of the geology of Clinton Co., N.Y.: N.Y. State mus. Ann. Rept. 13, p. 473-489. -----, 1895, Faults of Chazy Township, Clinton County, New York: Geol. Soc. America Bull., v. 6, p. 285- 296. , 1097, Report on Geology of Clinton County, New York: N.Y. State mus. Ann. Rept. 49, v. 2, p. 21-22, 499-513. 139 Cushing, H. P., 1899, Report on the boundary between the Potsdam and pre-Cambrian north of the Adiron- dackst N.Y. State Geol. Reph. 16, p. 1-27, map (1899)* N.Y. State Ann. Rept. 50, v. 2, p. 1-27 (1099). -, 1901, Geology of Rand Hill and vicinity, Clinton Co., Neur Yorkt N.Y. State Mus. Ann. Rept. 53, p. 3^-82. — — 1905, Geology of the northern Adirondack regioni N.Y. State IT!us. Bull. 95, 185 p. , 1908, Lower portion of the Paleozoic section in northwestern New Yorki Geol. Soc. America Bull., v. 19, p. 155-176. ---, 1911, Nomenclature of the Lower Paleozoic rocks of New Yorki Am. Jour. Sci., (4) v. 31, p. 35-145. -, 1916, Geology in the vicinity of Ogdensburg Briar Hill, Ogdensburg, and Red Mills quadrangles)! N.Y. State Mus. Bull. 191, 64 p. Cushing, H. P., et al., 1910, Geology of the Thousand Islands regTon (Alexandria Bay, Cape Vincent, Clayton, Grindstone and Theresa quadrangles)! N.Y. State Mus. Bull. 145, p. 1-194. Cushing, H. P., and Ruedemann, R., 1914, Geology of Saratoga Springs and vicinity (Saratoga and Schuylerville quadrangles)! N.Y. State Mus. Bull. 169, 177 p. Dietrick, R. V., 1957, Pre-Cambrian geology and mineral resources of the Brier Hill Quadrangle, New York! N.Y. State Mus. Bull. 354, 121 p. Dugas, J., 1949, Preliminary map of Perth map area, Lanark and Leeds Counties, Ontario* Dept, of Mines and Tech. Surveys, Geol. Surv. Canaoa, Paper 50-29, map and report. — ---, 1961, Perth, Lanark and Leeds Counties, Ontario! Geol. Surv. Canada, Map 1089-A. Emmons, E., 1838, Report of the second geological district of the State of New Yorki N.Y. State Geol. Surv., 2nd Ann. Rept., p. 185-252. 140 Emmons, E., 1842, Geology of New York, Part 2f Com prising the survey of the second geological district! Albany, N.Y., 437 p. Evans, 0. f., 1943, Effect of change of wave size on the size and shape of ripple markst Jour. Sed. Petrology, v. 13, p. 35-39. fisher, D. Hi., 1956, The Cambrian system of New York State. El slstema Cambrico, su paleogeografia y el problems de su baset XX Geologico Internacional, Mexico, Tomo II, parte II, p. 321-351* fisher, D. Hi., et al., 1962, Cambrian correlation chart of New Yor?T~statBi Geol. Survey, N.Y. State Mus. and Sci. Services, Albany, N.Y. flower, R. H., 1947, Cambrian and Canadian of Fort Ann, N.Y. (Abs.)t Geol. Soc. America Bull., v. 58, no. 12, pt. 2, p. 1190. fraser, F. J., 1931, Heavy minerals in the basal Ordovician sandstones of Ontario and Quebec! Geol. Surv. Canada, Sum. Rept. 1930, pt. D, p. 59-60. Haff, J. C., 1938, Preparation of petrofabric diagrams! Am. Mineralogist, v. 23, no. 9, p. 543-574. Hall, James, 1859, Paleontology of New York, v. 3, pt. 1, Albany, N ,Y . Hamblin, UJ. K., 1958, The Cambrian sandstones of northern Michigan! Michigan Geol. Survey, Pub. 51, 146 p. , 1961, Micro-cross-lamination of Upper Keweenawan sediments of northern Michigan! Jour. Sed. Petrology, v. 31, no* 3, p. 390-401. Harding, UJ, D., 1931, The relations of the Grenville sediments and the Potsdam sandstone in eastern Ontario! Am. Mines, v. 16, p. 430. Hyde, J. E., 1911, The ripples of the Bedford and Berea formations of central Ohio, with notes on the paleo- geography of that epoch! Jour. Geology, v. 19, p. 257-269. 141 Ingerson, E., 1939, Fabric criteria for distinguishing pseudo ripple marks from ripple marks (Abs.)i Geol. Soc. America Bull., v, 50, p. 1953; 1940, Geol. Soc. America Bull., v. 51, p. 557-569. Keith, I t !. L., 1946, Sandstone as a source of silica sands in southeastern Ontario* Ontario Dept. Itlines 55th Ann. Rept., v. L V, pt. V, 36 p. Kemp, J. F., 1B96, The Pre-Cambrian topography of the Adirondacks* N .Y. Acad. Sci. Trans. 15, p. 189- 190. Kemp, J. F., and Ailing, H. L., 1925, Geology of the Ausable Quadrangles* N .Y . State lYlus• Bull. 261, 126 p. Kemp, J. F., and Ruedemann, R., 1910, Geology of the ElizabBthtoum and Port Henry Quadranglest N.Y. State Iffus. Bull. 137, p. 7-173. Kiersch, G. A., 1950, Small scale structures and other features of the Navajo sandstone, northern part of the San Rafael Swell, Utahi Am. Assoc. Petroleum Geologists Bull. 34, p. 923-942. Kindle, E. I f f . , 1914, A comparison of the Cambrian and Ordovician ripple marks found at Ottawa* Jour. Geology, v. XXII, p. 704-705. -, 1917, Recent and fossil ripple mark* Geol. Survey Canada Ulus. Bull. 25, p. 1-56. Knight, S. H., 1929, The Fountain and Casper formations of the Laramie Basin* Univ. Wyoming Pub. Sci., Geology 1, no. 1, p. 1-32. Krumbein, S. C., 1 j41, Measurement and geological significance of shape and roundness of sedimentary particles* Jour. Sed. Petrology, v. 11, p. 64-72. Krynine, P. D., 1940, Petrology and genesis of the Third Bradford sand* Pa. State College Iffines Indus. Expt. Bull. 29, p. 1-134. -----, 1946, The tourmaline group in sediments* Jour. Geology, v. LIV, no. 2, p. 65-87. 142 Lahes, F. H., 1952, Field geology; 5th ed.) McGraw- Hill Book Co., Inc., New York, 883 p. Lane, D. Ui., 1963, Crosa-stratificatlon in San Bernard River, Texas, point bar depoaiti Jour. Sed. Petrology, v. 33, no. 2, p. 350-354. Logan, W. A., 1863, Geology of Canadat Geol. Surv. Canada Progress Rept. to 1863. Mackie, William, 1896, The sands and sandstones of eastern Moray) Edinburgh Geol. Soc. Trans., v. 7, p. 148-172. Mather, W. W«, 1643, Geology of New York, Part 1, comprising the survey of the first geological district! Albany, N.Y., 653 p. Maxson, J. H., and Campbell, I., 1934, Archean ripple mark in the Grand Canyon) Am. Jour. Sci.(5), v. 28, p. 298-303. 1939, Archean pseudo ripple mark in the Grand Canyont Am. Jour. Sci., v. 237, p. 606, Merrill, F. J. H., 1899, 51st Annual Report, Part 1, N,Y. State Mus., p. 137-180. Miller, A. J., 1911, Geology of the Broadalbin Quad rangle, Fulton-Saratoga Counties, Nee York) N.Y. State Mus. Bull. 143, 65 p. --- , 1916, Geology of the Lake Pleasant quadrangle, Hamilton County, New York) N.Y. State Mus. Bull. 182, 75 p. , 1919, Geology of the Schroon Lake quadrangle) N.Y. State Mus, Bull. 213-214, 102 p. McDowell, J, P., 1960, Cross-bedding formed by sand waves in Mississippi River point bar deposits (Abs.)) Geol. Soc. America Bull., v. 71, p. 1925. McKee, E. D., 1939, Some types of bedding in the Colorado River delta) Jour. Geology, v. 47, p. 64-81. , 1940, Three types of cross-lamination in Paleozoic rocks of northern Arizona) Am. Jour. SCi., v. 238, p. 311-824. 1 A3 McKee, E. D., 1953a, Studies In sedimentology of the Shinarump conglomerate of northeastern Arizona! U.S. Atomic Energy Comm. Tech. Rept, RIME-3089, A8 p. ---- , 1953b, Report of studies of stratification in modern sediments and in laboratory experiments! Office of Naval Research, Proj. Nonr 164(00), NR 081123, 61 p. McKee, E. 0., and Resser, C., 1945, Cambrian history of the Grand Canyon region, Part 1, Stratigraphy and ecology of the Grand Canyon Cambrian! Carnegie Inst. UJash., Pub. no. 563, p. 1-163. McKee, E. D., and Sterrett, T. S., 1961, Laboratory experiments on form and structure of longshore bars and beachesi Geometry of sandstone bodies, sym posium of the Am. Assoc. Petroleum Geologists, Peterson, J. A., and Osmond, J. C., eds., p. 13- 28. IMcKee, E. 0., and Weir, G. UJ., 1953, Terminology for stratification and cross-stratificationi Geol. Soc. America 8ull., v. 64, p. 381-390. Mclver, N. L., 1961, Upper Devonian marine sedimen tation in the central Appalachians! Unpublished dissertation, The Johns Hopkins Univ., Baltimore, Maryland. Nelson, A. E., et al.. 1956, Geologic map of the Chateaugay quadrangle, New York! U.S. Geol. Survey Mis. Geol. Inv. Map 1-168. Neuland, D. H., and Vaughan, Henry, 1942, Guide to the geology of the Lake George region! MY. State Mus. Handbook 19, 234 p. Pelletier, 8. R., 1958, Pocono paleocurrents in Pennsylvania and Maryland! Geol. Soc. America Bull., v. 69, p. 1033-1064. Pettijohn, F. J., 1957a, Sedimentary Rocks, 2nd ed.i Harper & Brothers, New York, 718 p. t 1957b, Paleocurrents of Lake Superior Precambrian quartzitesi Geol. Soc. America Bull., v. 68, p. 469-480. 144 Pincus, H. J., 1956, Some vector and arithmetic operations on two-dimensional variates, utith application to geological datat Jour, Geology, v. 64, p. 533-557, Postel, A, Ul.f 1952, Geology of Clinton County, magnetite District, New York* U . 5. Geol, Survey Prof. Paper 237, 88 p, Postel, A. iJ/., e^t al.. 1956, Geologic map of the malone quadrangle, New York! U . 5. Geol, 5urvey mis. Geol, Inv. map 1-167. , 1959, Geology of the Nicholville quadrangle, New Yorki U. S. Geol. Survey map GQ-123. Potter, P. E., 1955, Petrology and origin of the Lafayette gravel, Part 1, mineralogy and petrologyi Jour. Geology, v, 63, p, 1-30. Potter, P, E., and Olson, J. S., 1954, Variance components of cross-bedding direction in some fossil Penn sylvanian sandstones of the eastern interior basin, geological application! Jour, Geology, v. 62, p. 50-73. Powers, m. C., 1953, A new roundness scale for sediment ary particlest Jour. 5ed. Petrology, v. 23, p. 117-119. Reed, J. C,, 1934, Geology of the Potsdam quadrangle! N.Y. State mus. Bull. 297, 98 p. Reiche, P., 1938, An analysis of cross-laminationi Coconino sandstone! Jour. Geology, v. 46, p. 905- 932. Sandford, B. V., and Guillian, A. G«, 1959, Subsurface stratigraphy of Upper Cambrian rocks in southwest Ontario! Geol. Survey Canada Paper 58-12. Schwarzacher, U/., 1953, Cross-bedding and grain size in the Lower Cretaceous sands of East Angliai Geol. mag., v. 90, p. 322-330. Shrock, R. R., 1948, Sequence in layered rocksi McGraw- Hill Book Co., Inc., New York, 507 p. 145 Siever, R., and Potter, P. ID*, 1956, Sources of basal Pennsylvanian sediments in the eastern interior basin, Pari. 2, Sedimentary petrologyi Jour. Geology, v. 64, p. 317-335. Stokes, U/. I., 1953, Primary sedimentary trend indicators as applied to ore finding in the Carrizo fountains, Arizona and Nbui Mexico, Part It U.S. Atomic Energy Comm. Tech. Rept. RME-3043 (pt. l), 48 p. Trow, J. 11/., 1948, ThB Sturgeon quartzite of the MenomineB district, Michigan! Unpublished Ph.D. dissertation, Univ. Chicago. Twenhofel, U/. H., 1961, Treatise on sedimentation, 2nd ed.t Dover Publications, Inc., New York, v. 1, p. 1-460. Ulrich, E. 0., and Cushing, H. P., 1910, Age and relations of the Little Falls dolomite (Calciferous) of the Mohawk Valleyi N.Y. State Mus. Bull. 140, p. 97- 140. Van Ingen, G., 1902, The Potsdam sandstone of the Lake Champlain basin, Notes on field work (90)t N.Y. State Mus. Bull. 52, p. 529-545. Whitaker, J. C., 1955, Direction of current flow in some lower Cambrian elastics in Marylandi Geol. Soc. America Bull., v. 66, p. 763-766. Wiesnet, D. R., 1961, Composition, grain size, roundness, and spherocity of the Potsdam sandstone (Cambrian) in northeastern New Yorkt Jour. Sed. Petrology, v. 31, no. 1, p. 5-14. Wilson, A. E., 1940, Casselman, Russell, Dundas, Stormont, Prescott, Carleton, and Papineau Counties, Ontario and Quebeci Dept. Mines and Resources, Mines and Geol. Branch, Geol. Survey Canada, Map 587-A. — -— , 1941a, L'Orlginal, Ontario and QuBbeci Dept. Mines and Resources, Mines and Geol. Branch, Geol. Survey Canada, Map 662-A. -----, 1941b, Valley Field, Quebec and Ontario! Dept. Mines and Resources, Mines and Geol. Branch, Geol. Survey Canada, Map 660-A. 146 Wilson, A. E., 1941c, (tiaxville, Ontario and Quebect Dept, mines and Resources, mines and Geol. Branch, Geol. Survey Canada, lYlap 661-A. --— 1942, Prescott, Ontario! Dept, mines and Resources, mines and Geol. Branch, Geol. Survey Canada, map 710-A . --- , 1946a, Geology of the Ottawa-St. Lawrence Lou/land, Ontario and Quebect Geol. Survey Canada memoir 241, 65 p • ----- , 1946b, Ottawa-Cornwall, Ontario and Quebect Dept, mines and Resources, mines and Geol. Branch, Geol. Survey Canada memoir 241, map 852-A. --, 1954, Ottawa, Carleton, Gatineau, and Papineau Counties, Ontario and Quebec! Dept, mines and Tech. Surveys, Geol. Survey Canada, map 1038-A. Wilson, m. E., 1921, The relationships of the Paleozoic to the Pre-Cambrian along the southern border of the Lewiston Highlands in southeastern Ontario and the adjacent portions of Quebec* Royal Soc. Canada, Proc. and Trans., 3rd ser., 14, sec. 4, p. 15-24. — ---, 1931a, Ripple marks in the Lower Paleozoic of Ottawa valleyi Canada min. Jour., 52, no. 14, p. 347-348. --, 1931b, Ripple marks near Perth, Lanark County, Dntarioi Canada Field Nat., 45, no. 2, p. 25-27. 1937, Erosional intervals indicated by contacts in the vicinity of Ottawa, Ontario! Royal Soc. Canada, Proc. and Trans., 3rd sec., 31, sec. 4, p. 45-60. , 1938a, Ottawa sheet (east half), Carleton and Hull Counties, Ontario and Quebect Dept, mines and Resources, mines and Geol. Branch, Geol. Survey Canada, map 413-A; included in Geol. Survey Canada memoir 241, 1946. , 1938b, Ottawa sheet (west half), Carleton and Hull Counties, Ontario and Quebect Dept, mines and Resources, mines and Geol. Branch, Geol. Survey Canada, map 414-At included in Geol. Survey Canada memoir 241, 1946. 147 Wilson, M. E., 1940, Nepean, Carleton, Lanark, Grenville, Dundas, Gatineau, and Papineau Counties, Ontario and Quebect Dept* Mines and Resources, Mines and Geol. Branch, Geol. Survey Canada, Map 588-A. UJynne-Ediwards, H. R., 1956, Geology of UJestport map area, Leeds, Frontenac, and Lanark Counties, Ontario! Geol. Survey Canada, Map 26-1959. Yeakel, Jr., L. S., 1962, Tuscarora, Juniata, and Bald Eagle paleocurrents and palsogeography in the Central Appalachianst Geol. Soc. America Bull., v. 73, p. 1515-1540. AUTOBIOGRAPHY I, Thomas Leonard LBwis, mas born on July 15, 1934, in Rochester, New York. I attended the Rochester public schools for my primary and secondary education. I re ceived my undergraduate training at Oberlin College, which granted me the Bachelor of Arts degree in 1956. I was granted the Master of Arts degree in 195B from the University of Rochester. A year of teaching experience was acquired at Alfred University, where I taught courses both for the University and the New York State School of Ceramic Engineering. I taught geology courses for a National Science Foundation seminar for high-school teachers during the summer of 1950. At the Ohio State University, I have held teaching assistantships for several years and the Bownocker Fellowship for one year. In the spring of 1963, I taught a geology course at the Lima Branch Campus. At present, I am teaching full time at the Lakewood Branch of the Ohio State University. 148 o Tta** ITTAWA P^TH^S OENSBURG POTSDAM^ PLATE I / CROSS-BEDDING , ;£t o w n j LAKE IN THE POTSD> ONTARIO NEW YORK. ON LEGEND N K*M atUfraai M l« Oala ara |>M H< ia tro 10* M arvala a rf f M ta l aa taa feaaia af aaifcat fttaaaaiy M' ftaaa aia*»aw af hafitaatailf aamctaa aiiamfli itMt-faffint Btracfiaaa. Naaaali ratfaaaat lafal % •w ntar *f craaa-M B laf raaBiafi af aacfc laaatlfir. UTICA In n alad i aataraa aa'tar* af Iha Piiifaa (Na»aa^ •aaBafaaa. IP AAZIMUTH DISTRIBUTION \M (NEPEAN) FORMATION. fTARIO AND QUEBEC 9 0 9 10 19 all*! SCALE ^GLENS FALLS NEW NEW YORK ^AMSTERDAM &DENSBURG PLATE II - n n DISTRIBUTION C WATER TO WN ^ LAKE THE POTSI O N TA R 10 - ~ v - LEGEND N All mM turmantt «r* <"•«* normal to ripple Imaation in dither the current direction ornormal to «wov» movamant > LOCALITY NUMBER V #>— 46 -#----- OSCILLATION RIPPLES (some undifferentiated ore marked — ?) VECTOR RESULTANT OF CROSS * BEDDING LENGTH PROPORTIONAL TO VECTOR MAGNITUDE ______CURRENT RIPPLES SAND LI NEAT I ON APPROXIMATE OUTCROP PATTERN OF THE POTSDAM FORMATION DF PALEOCURRENTS IN DAM FORMATION 9 ° 5 a* ip Miles SCALE Z 1 AMSTERDAM A.