that ranges from a roof zone of gra- nophyric granite to an intermediate zone of aplite to a core of porphyritic granite. The intrusion shows a progressive devel- opment from west to east of a coarse and porphyritic texture and an increase in mafic minerals. The textural and miner- alogical variations appear to be gradation- al with no evidence for multiple intru- sions. The granophyre zone is fine grained (0.5–2 mm) and has a micrographic tex- ture. It encompasses an area from the west contact zone to just east of Capitan Gap where it grades into an equigranular tex- tured aplite (Fig. 3). The aplite zone extends eastward to the saddle at the head of Hinchley Canyon and also crops out at Capitan Gap where deeper parts of the pluton are exposed. The porphyry zone FIGURE 2—Location of the study area in the Capitan Mountains. Base map is the U.S. Geological stretches from the saddle at the head of Survey’s topographic map of Roswell quadrangle 1:250,000 scale series. Hinchley Canyon to the east end of the primary factors in the generation of rock lish the age of the rock glaciers and to pre- New Mexiiico glaciers (Morris, 1981). Frost wedging sent a chronology based upon activity, and supplies the debris for the development of (4) to attempt to relate the distribution of GEOLOGY rock glaciers and occurs under periglacial the older and younger forms to climatic climates that are characterized by fre- fluctuation and to the lithology and struc- Science and Service quently recurring freeze and thaw (Flint, ture of the pluton. • 1971, pp. 271–274; Washburn, 1980, pp. ISSN 0196-948X Volume 21, No. 3, May 73–79). This process is promoted by snow Geographic and geologic setting cover of short duration and enough mois- 1999 ture in the ground for cryofraction to The Capitan Mountains are located in occur (Corté, 1987). Climatic elements Lincoln County, New Mexico, approxi- Editors: Jane C. Love, Nancy S. Gilson, Jeanne Deardorff conducive to the development of intersti- mately 80 km northwest of Roswell and 40 Cartographer: Kathryn Glesener tial ice in rock glaciers are (1) sufficient km northeast of Ruidoso in south-central EDITORIAL BOARD precipitation for the formation of the ice New Mexico (Fig. 1). The range extends in and (2) temperatures that are low enough Steve M. Cather, NMBMMR, Chairman an east-west direction for approximately Thomas Giordano, NMSU for the maintenance and creep of the ice 32 km and is approximately 7 km wide. Laurel B. Goodwin, NMIMT (Wahrhaftig and Cox, 1959). Interstitial ice West Mountain is a nearly isolated upland Published quarterly by (permafrost) can exist in rock glaciers if with an altitude of 2,272 m and is separat- New Mexico Bureau of Mines and the mean annual temperature at ground Mineral Resources ed from the main part of the mountains by a division of New Mexico Institute of level is 0– -1°C especially if the snow cover Capitan Gap (Fig. 2). The summit east of Mining and Technology is thin and of short duration (Péwé, 1983). Capitan Gap is 2,600–3,050 m in altitude Rock-glacier debris is derived primarily and rises approximately 900 m above the BOARD OF REGENTS Ex-Officio from cliffs undergoing the blocky weath- surrounding alluvial-covered lowlands. Gary Johnson, Governor of New Mexico ering that occurs in massive igneous, The head of Hinchley Canyon and Pierce Michael S. Davis, Superintendent of Public Instruction metamorphic, and sedimentary rocks Canyon Pass are well-defined saddles that Appointed where two or three structural trends of break the relatively flat crest (Fig. 3). The Robert E. Taylor, Pres., 1997–2003, Silver City Randall E. Horn, Sec./Treas., 1997–2003, Albuquerque joints are present (Evin, 1987). The process saddle at the head of Hinchley Canyon Ann Murphy Daily, 1999–2004, Santa Fe is particularly prevalent if two joint trends divides the range into western and eastern Sidney M. Gutierrez, 1997–2001, Albuquerque are parallel and orthogonal to each other sections, which have distinctive geologic Kathryn E. Wavrik, Student Mem., 1999–2000, Socorro and the other set is oblique. Well-devel- and physiographic attributes noted below. New Mexico Institute of Mining and Technology President ...... Daniel H. López oped bedding planes in sedimentary rocks Summit Peak and Capitan Peak are promi- New Mexico Bureau of Mines and Mineral Resources are also an important control. Frost wedg- nent landmarks above 3,050 m in the east- Director and State Geologist ...... Charles E. Chapin ing is effective in dislodging blocks and ern part of the range. The north and south Subscriptions: Issued quarterly, February, May, slabs from cliffs with blocky structure flanks of the mountains are cut by numer- August, November; subscription price $10.00/cal- because freeze-thaw action pries apart endar year. ous steep-walled canyons with maximum Editorial Matter: Articles submitted for publication rock along joints, fractures, and bedding depths of approximately 330 m. Many should be in the editor’s hands a minimum of five planes. small canyons and ravines are tributaries (5) months before date of publication (February, May, August, or November) and should be no The purpose of this paper is: (1) to pre- to the larger canyons. longer than 20 typewritten, double-spaced pages. sent criteria for distinguishing rock glaci- The Capitan Mountains are formed by All scientific papers will be reviewed by at least two people in the appropriate field of study. Address ers of two ages in the Capitan Mountains an intrusion of mid-Tertiary age com- inquiries to Jane C. Love, Editor of New Mexico using physiographic preservation and soil posed of alkali feldspar granite with con- Geology, New Mexico Bureau of Mines and Mineral development, (2) to note the geographic tact zones that are poorly exposed except Resources, Socorro, New Mexico 87801-4796. Published as public domain, therefore reproducible without distribution of the rock glaciers in rela- at the east and west ends (Allen and permission. Source credit requested. tionship to the textural and mineralogical McLemore, 1991). It is a single but textu- Circulation: 1,000 zones of the Capitan pluton, (3) to estab- rally and compositionally zoned pluton Printer: University of New Mexico Printing Services

58 August 1999 New Mexico Geology FIGURE 3—East-west cross section along the south side of the Capitan Mountains showing major topographic features, distribution of the textural zones, and the areal extent of older and younger rock glaciers. Location of the textural zones is from Allen and McLemore (1991, p. 118, fig. 7). 1, average alti- tude of rock-glacier heads; 2, average altitude of rock-glacier fronts. Vertical exaggeration approximately x 2.6.

Summit Peak Hinchley Canyon

FIGURE 4—South side of the Capitan Mountains showing distribution of talus and frost rubble (light areas) east and west of Hinchley Canyon. The deposits are more extensive on slopes eroded in aplite west of the canyon than on slopes eroded in porphyry to the east. Photograph by Francis G. Varney. mountains and contains as much as 20% for south-central New Mexico (Van described the forms in the western part of phenocrysts of anorthoclase and, rarely, Devender et al., 1984) suggest the follow- the range in detail. The average altitude of plagioclase. The distribution of vein and ing approximations of current mean annu- the heads is approximately 2,574 m, and breccia deposits in the range indicates that al temperatures for the Capitan Moun- the average altitude of the fronts is the granophyre and aplite zones are more tains: 5–8°C for the slopes (2,300–2,750 m) 2,474 m (Table 1). The lengths are between intensely fractured than the porphyry and 3°C for the crest (3,000 m). 56 and 1,565 m (Table 1), and the widths zone (McLemore and Allen, 1991). Vegetation zonation in the Capitan average approximately 70 m. The rock Rock-fall talus accumulates below cliffs Mountains ranges from desert grassland glaciers in ravines and tributary canyons and steep slopes, and frost rubble forms near the base to the spruce-fir association are the extensions of talus at the drainage extensive sheets on the upper slopes of the on the crest (Martin, 1964). The pinyon- heads. Those on the floors of major mountains; both obscure the bedrock in juniper association extends up to an aver- canyons are composed of talus that accu- many areas (Fig. 4). Some rubble sheets age altitude of approximately 2,200 m on mulated as sheets along the base of side have undulating surfaces formed by many the lower slopes. The transition associa- walls and head walls. Frost rubble small ridges and furrows. The ridges and tion is between approximately 2,200 and encroaches upon the heads and flanks of furrows are parallel to the contours indi- 2,700 m, and the spruce-fir association is many rock glaciers on canyon floors and cating movement downslope because of above 2,750 m on the upper slopes and suggests downslope movement of debris solifluction or frost creep. Talus and frost crest. Aerial photographs reveal that the after the rock glaciers became inactive rubble, nearly devoid of soil and vascular slopes and crest of the mountains are more (Fig. 6). plants, cover approximately 30–60% of heavily forested in the eastern part of the The rock glaciers have steep fronts 5–60 slopes eroded in granophyre and aplite range in porphyry terrane as compared to m high that slope approximately 30° (Fig. compared to approximately 20–30% for the slopes and crest in the west in gra- 7). Heads merge with talus on the steep slopes eroded in porphyry. nophyre and aplite terrane. mountain slopes, and the surfaces above No long-term weather records exist for the fronts slope downstream at approxi- the Capitan Mountains. Stations at Description mately 15°. Flanks are steep embankments Arabela, Baca Ranger Station, and Capi- 5–10 m high and commonly are separated tan, however, suggest a mean annual pre- One hundred twenty-four rock glaciers from the sides of canyons and ravines by cipitation of 40–50 cm near the base developed below talus at the heads of gullies. Lateral ridges 1–5 m high delin- (Gabin and Lesperance, 1977). The slopes ravines and small tributary canyons and eate the flanks of many rock glaciers and may receive 50–75 cm and the crest more on the floors of major canyons on the bend to form transverse ridges at the crest than 75 cm of precipitation annually (Tuan north and south sides of the Capitan of the fronts. On many rock glaciers, et al., 1969). Long-term weather records Mountains (Fig. 5). Blagbrough (1976, depressed areas are 1–5 m below lateral from Fort Stanton (Kunkel, 1984) and the 1991) observed the distribution of rock ridges and extend from the crest of the mean annual lapse rate of 0.72 cm/100 m glaciers throughout the range but only fronts to the heads. Longitudinal and

New Mexico Geology August 1999 59 FIGURE 5—Localities of older and younger rock glaciers in the Capitan Mountains. Rock-glacier symbols denote positions of the fronts. Base maps are 1 the U.S. Geological Survey’s topographic maps of Capitan Pass, Capitan Peak, Encinoso, and Kyle Harrison Canyon 7 ⁄2-min quadrangles. transverse ridges and furrows are com- are present in the eastern part of the Soil and vascular plants cover 50–85% of mon surface features that result in a hum- mountains below slopes eroded in por- the surfaces on the older rock glaciers. The mocky topography with a relief of approx- phyry (Table 2). They are moderately dis- soil is composed of a dark-gray eolian imately 3 m on some surfaces. Conical sected and show good preservation of the mantle overlain by a dark-brown horizon pits, with a mean depth of approximately tongue-shaped form. The gross features, formed by decomposed or partially 3 m, and oblique ridges and furrows that such as steep fronts, flanks, lateral ridges, decomposed organic material (Fig. 8). The trend at approximately 45° to the apparent and depressed areas, are somewhat sub- eolian mantle is 20–30 cm thick and com- direction of movement are less commonly dued. Longitudinal and transverse ridges posed primarily of fine sand and silt with developed. and furrows are either poorly defined or larger fragments that range to pebble size. Rock glaciers of two ages are distin- unrecognizable on aerial photographs. The clasts are angular grains of quartz and guished based upon the preservation of The debris of the rock glaciers is formed feldspar, and no well-rounded, frosted the topographic expression and soil devel- from blocks and clasts of porphyry with quartz grains were observed. The grains opment. Thirty-eight older rock glaciers average diameters of 30–90 cm. are not coated with either organic stain or calcium carbonate and appear extremely TABLE 1—Comparative altitudinal and morphological data for rock glaciers in the Capitan Moun- fresh. The eolian mantle contains large tains. amounts of organic material possibly with All rock Rock glaciers Rock glaciers some calcium carbonate. The upper hori- zon is approximately 7.5 cm thick and glaciers north side south side composed of large wood fragments and Number 124 72 52 decomposed organic debris. It also con- tains sand and silt grains similar to those Mean altitude 2,474 2,443 2,517 in the eolian mantle. of fronts (m) The head of an older rock glacier is over- ridden by the front of a younger form in Range in altitude 2,244–2,689 2,244–2,659 2,378–2,689 of fronts (m) Las Tablas Canyon on the north side of the range (Fig. 9). The older rock glacier is Mean altitude 2,574 2,542 2,605 composed of two talus tongues, both of of heads (m) which have well-defined fronts and flanks. The surface is covered by an eolian Range in altitude 2,305–2,841 2,305–2,841 2,427–2,829 mantle with a maximum thickness of of heads (m) approximately 30 cm overlain by approxi- Mean length (m) 305 306 288 mately 7.5 cm of decomposed to partly decomposed organic debris. The front of Range in length (m) 56–1,565 56–1,565 62–1,105 the younger rock glacier rises abruptly above the older surface, and debris from TABLE 2—Numbers of older and younger rock glaciers in the eastern and western parts of the the base extends into the depressed area of Capitan Mountains. the upper tongue of the older form (Fig. Eastern section Western section 10). porphyry terrane aplite and granophyre Seventy-two younger rock glaciers are terrane present on West Mountain and in the main upland of the Capitan Mountains between Older rock glaciers 38 0 Capitan Gap and the saddle at the head of Younger rock glaciers 14 72 Hinchley Canyon below slopes eroded in granophyre and aplite. Fourteen younger

60 August 1999 New Mexico Geology

FIGURE 10—Older rock glacier overridden by the front of a younger form in Las Tablas Canyon on the north side of the Capitan Mountains. The man in the center of the photograph is at the contact of the older and younger debris. The surface of the older rock glacier is obscured by soil and vegetation, whereas the front of the younger form is nearly devoid of soil and vegetation. Photograph by John C. Varney. forms in the eastern part of the range are about the same degree of preserved sur- of Lake Estancia at 24.3 ka, which marks below slopes eroded in porphyry. The face features and about the same amount the onset of cold/moist conditions. He younger rock glaciers have a well-pre- of area covered by soil and vegetation, also presents evidence for a long preced- served tongue-shaped form and are less which implies that they formed during a ing cold/dry sub-pluvial interval, which dissected than the older rock glaciers. The single periglacial episode. he correlates with the early and middle fronts, flanks, lateral ridges, and de- Soil and vascular plants usually cover Wisconsin periods. pressed areas are well defined and show approximately 1–15% of the surfaces of Allen (1991) recognized two major high little modification by erosion (Fig. 7). The younger rock glaciers. The soil is similar to stands for the lake. The older occurred longitudinal and transverse ridges and the upper horizon on the older rock glaci- between 20 and 15 ka during late Wiscon- furrows are sharp and easily recognizable ers and has an average thickness of sin maximum glacial conditions. It was on aerial photographs. approximately 7.5 cm in the western part followed by a low stand between 15 and The younger rock glaciers in the western of the range. It is dark brown in color and 14 ka when warmer and drier conditions part of the range are composed of debris is formed by decomposed and partially prevailed. The younger high stand began derived from granophyre and aplite. The decomposed organic material mixed with about 13.7 ka and was followed by signif- angular blocks and slabby clasts range in sand and silt. It fills voids between the icant desiccation of the lake between 12 diameter from 15 cm to 2 m and average blocks and slabby clasts. Trees and shrubs and 11 ka. A minor rise in the lake level at approximately 60 cm. Many smaller frag- grow in the soil and project through the about 10.5 ka is recorded before the final ments are less than 30 cm in diameter and debris on some surfaces. desiccation phase, which was apparently may have been transported by water. The underway by about 10 ka. debris on the lateral ridges commonly is Age Glacial moraines were reported in an larger than that on the frontal faces and in alpine valley and small cirque on the the depressed areas. Most fragments are No direct dating methods exist for the northeast side of Sierra Blanca Peak oxidized, and some have undergone frost rock glaciers in the Capitan Mountains at (Richmond, 1963, 1986). Richmond (1963) shattering while on the surfaces of rock the present time. Age inferences, however, mapped two older moraines of probable glaciers. The debris is stable, and lichens can be made using paleoclimatic data Bull Lake age and three younger moraines cover 20–30% of exposed faces. from the Estancia Basin in central New thought to be Pinedale (late Wisconsin) in Eighteen rock glaciers on canyon floors Mexico (Hawley, 1993) and the glacial and age. The Bull Lake moraines are character- west of Summit Peak have arcuate ridges periglacial deposits on Sierra Blanca Peak ized by broad crests, smooth slopes, and and furrows along the flanks, which sug- in south-central New Mexico (Richmond, broadly scattered surface boulders. They gest that they developed from lobate rock 1986). Allen (1991) and Allen and bear mature soils approximately 90 cm glaciers that coalesced on the canyon floor. Anderson (1993) have established a late thick with a well-developed B horizon. Seven younger rock glaciers east of Wisconsin chronology for pluvial Lake Pinedale moraines have irregular form, Summit Peak are composed of two talus Estancia in the Estancia Basin using radio- abundant surface boulders, and immature tongues, both of which have steep fronts, carbon dating of organic remains and soils approximately 25 cm thick. Because lateral ridges, and depressed areas. The detailed studies of basin-fill stratigraphy of differences in surface form and boulder upper tongue appears to have overridden and sedimentology (Table 3). Bachhuber frequency, Shroba (1977) suggested that the head of the lower. Both tongues have (1989) dates the initial fresh-water phase part of the inner Bull Lake moraine of

62 August 1999 New Mexico Geology Richmond is Pinedale in age. TABLE 3—Tentative correlation of late Wisconsin pluvial, glacial, and periglacial events in south- Shroba (1977, 1991) describes two rock- central New Mexico. glacier deposits on Sierra Blanca Peak. The Estancia Basin Sierra Blanca Peak Capitan older is thought to be late Pinedale in age Ka (Allen, 1991) (Richmond, 1986) Mountains (about 14 ka) and was previously mapped (Shroba, 1991) (This report) as Pinedale till by Richmond (1963). 10 According to these interpretations two Minor high stand Bull Lake moraines and two Pinedale (ca 10.5–10 ka) moraines are present. The older rock glac- 11 ier is covered by a loessal matrix 60–110 Desiccation cm thick and is probably latest Pinedale in (ca 12–11 ka) 12 Younger rock glacier age. The deposit extends approximately (ca 12 ka) 800 m through the Pinedale moraines and part way through the Bull Lake moraines 13 Younger high stand and may have formed during the reces- (ca 13.7–12 ka) sional episode of the Pinedale glaciation. The younger rock glacier may be Temple 14 Older rock glacier Younger rock glaciers Lake in age (about 12 ka). It is a small Low stand (ca 14 ka) deposit approximately 125 m in length (ca 15–14 ka) near the cirque headwall and is mantled 15 Loess by approximately 40 cm of Holocene loess. The younger Pinedale moraine on Sierra 16 Blanca Peak may be correlative with the glacial maximum high stand of Lake Estancia. The older rock-glacier deposit on 17 Glacial maximum Younger Pinedale Older rock Sierra Blanca Peak probably was active high stand moraine glaciers near the beginning of the younger high (ca 20–15 ka) stand of Lake Estancia, and the younger 18 rock glacier may have been formed at the close of the younger high stand as sug- 19 gested by the dates cited for the two areas. Much of the loessal matrix on the rock- glacier deposits may have accumulated 20 during the desiccation phase (12–11 ka) of Lake Estancia when warmer and drier conditions prevailed. Blagbrough (1991) noted that the soils on were much more severe and of longer the mafic minerals in the pluton at that the younger rock glaciers in the Capitan duration at the higher altitudes on Sierra locality. More intense chemical weather- Mountains are similar to those on the Blanca Peak resulting in barren mountain ing of the bedrock apparently results in Temple Lake moraines (12 ka) of Rich- slopes above timber line exposed to wind thicker soil, which promotes forest mond (1963) in the Sangre de Cristo erosion for long periods of time. growth. The thicker soil helps protect the Mountains of northern New Mexico. Blagbrough (1991) suggested that the bedrock from freeze-thaw action and Nonetheless, these forms may be late older rock glaciers in the Capitan restricts the formation of talus and frost Wisconsin in age (about 14 ka) because of Mountains were of Bull Lake age using the rubble east of the saddle at the head of the time involved in the accumulation of glacial chronology on Sierra Blanca Peak. Hinchley Canyon. The scarcity of soil, as fines on the surface. In addition, the They are now hypothesized to be of late well as the well-developed fracture sys- periglacial record in the cirque on Sierra Wisconsin age (20–15 ka) because of the tem, in the granophyre and aplite zones Blanca Peak indicates only minimal cool- good preservation of the gross features enables blocks and slabs to be dislodged ing during Temple Lake time (12 ka), and weak soil development. Thus, they easily by frost action, resulting in the gen- which would seem to preclude the preser- may be contemporaneous with the eration of large volumes of debris. vation of interstitial ice in the Capitan younger Pinedale moraine on Sierra The characteristics of rock glaciers in the Mountains. The sharp constructional relief Blanca Peak and the glacial maximum eastern part of the Capitan Mountains and restrictive development of soil and high stand of Lake Estancia. The eolian indicate two late Wisconsin periglacial vascular plants on the younger forms mantle on the older forms may have been episodes separated by a period of warmer implies movement near the close of the deposited during the warm/dry episode and drier conditions. The climate under late Wisconsin (about 14 ka). that followed the maximum high stand of which the older rock glaciers were gener- The climatic history of the region sug- Lake Estancia. ated was of sufficient intensity and dura- gests that the younger rock glaciers in the tion to produce large volumes of talus and Capitan Mountains may be correlative Discussion to mobilize the talus into rock glaciers with the older rock glacier on Sierra below slopes eroded in porphyry. The Blanca Peak and the beginning of the The distribution of talus and frost rubble snow cover probably was thin and of short younger high stand of Lake Estancia (13.7 in the Capitan Mountains indicates that duration, which favored intense freeze- ka; Table 3). The thick cover of loessal the granophyre and aplite zones are more thaw action. The mean annual tempera- matrix (60–110 cm) on the older rock glac- susceptible to freeze-thaw action than the ture was below freezing, which resulted in ier deposit on Sierra Blanca Peak as com- porphyry zone. Production of debris the formation and preservation of intersti- pared to a soil cover of about 7.5 cm on the appears to be controlled by the chemical tial ice. younger rock glacier in the Capitan composition and intensity of fracturing of The earlier periglacial episode was fol- Mountains can be explained by the 1,000 the pluton when favorable climatic condi- lowed by warmer and drier conditions, m difference in altitude between the two tions exist. The heavy forest growth in the which terminated rock-glacier activity and areas. Periglacial conditions probably eastern part of the range may be related to

New Mexico Geology August 1999 63 initiated a period of eolian deposition on separated by a period of warmer and drier trout (Oncorhynchus clarki) in pluvial lakes of the older surfaces. The composition and conditions. The distribution of older and the Estancia Valley, central New Mexico: texture of the sand and silt grains in the younger forms appears to be controlled by Geological Society of America, Bulletin, v. 10, eolian mantle suggest that it was locally structure and lithology of the bedrock, pp. 1543–1551. derived from the erosion of the pluton although the younger forms in the eastern Blagbrough, J. W., 1976, Rock glaciers in the Capitan Mountains, south-central New and/or from alluvial deposits around the part of the mountains are not clearly Mexico (abs.): Geological Society of America, base of the mountains. understood. The absence of observable Abstracts with Programs, v. 8, pp. 570–571. A later periglacial episode resulted in rock glaciers showing the characteristics Blagbrough, J. W., 1991, Late Pleistocene rock the generation of 14 younger rock glaciers, of older forms in the western part of the glaciers in the western part of the Capitan possibly at localities where the porphyry range also is subject to interpretation but Mountains, Lincoln County, New Mexico: is more intensely fractured. The presence may be due to the reactivation of older description, age and climatic significance; in in Las Tablas Canyon of an older rock forms during the later periglacial episode. Barker, J. M., Kues, B. S., Austin, G. S., and glacier down canyon from the front of a The older rock glaciers in the eastern part Lucas, S. G. (eds.), Geology of the Sierra younger form suggests that the later of the range were not reactivated during Blanca, Sacramento, and Capitan ranges, periglacial episode was less severe and/or the less severe climate of the later peri- New Mexico: New Mexico Geological Society, Guidebook 42, pp. 333–338. of shorter duration than the earlier glacial episode because granite prophyry Corté, A. E., 1987, Rock glacier taxonomy; in episode. This hypothesis is supported by is less susceptible to freeze-thaw action Giardino, J. R., Shroder, J. F., Jr., and Vitek, J. the stratigraphic record in the Estancia than the aplite and granophyric granite to D. (eds.), Rock glaciers: Allen and Unwin, Basin, which demonstrates that the climat- the west, which resulted in a scarcity of Boston, pp. 27–39. ic changes during the full glacial high blocky debris necessary for rock-glacier Evin, M., 1987, Lithology and fracturing control stand were more profound and of longer movement. The rock glaciers suggest a of rock glaciers in southwestern Alps of duration than those of the younger high late Wisconsin climatic history for the France and Italy; in Giardino, J. R., Shroder, J. stand (Allen, 1991; Allen and Anderson, Capitan Mountains comparable to that F., Jr., and Vitek, J. D. (eds.), Rock glaciers: 1993). indicated by glacial and periglacial Allen and Unwin, Boston, pp. 83–106. Near the close of the late Wisconsin deposits on Sierra Blanca Peak and the Flint, R. F., 1971, Glacial and Quaternary geolo- (about 12 ka) the climate again moderated sedimentary record in the Estancia Basin. gy: John Wiley and Sons, New York, 892 pp. and resulted in the cessation of processes Detailed mapping of and an extensive soil Gabin, V. L., and Lesperance, L. E., 1977, New that formed rock glaciers. The organic sampling program on the forms in the Mexico climatological data: W. K. Summers and Associates, Socorro, 436 pp. debris on the older and younger rock glac- eastern part of the range may indicate a Giardino, J. R., and Vitek, J. D., 1988, The signif- iers probably formed during the Holocene more complex late Wisconsin history than icance of rock glaciers in the glacial- (11 ka to present) when warmer condi- that presented in this paper. periglacial landscape continuum: Journal of tions prevailed. The presence of partially Quaternary Science, v. 3, pp. 97–103. decomposed organic debris indicates that ACKNOWLEDGMENTS—The author wishes Hawley, J. W., 1993, Geomorphic setting and the process continues at the present time. to extend his appreciation to William O. late Quaternary history of pluvial-lake basins The absence of observable rock glaciers Hatchel, Francis G. Varney, and John C. in the southern New Mexico region: New with the characteristics of older forms in Varney who assisted in the field, and to Mexico Bureau of Mines and Mineral the western part of the Capitan Mountains Leigh L. Sprague who provided an aerial Resources, Open-file report 391, 28 pp. implies one of three possibilities: (1) the reconnaissance of the Capitan Mountains. Kunkel, K. E., 1984, Temperature and precipita- older rock glaciers never formed; (2) they Thanks are due also to David W. Love for tion summaries for selected New Mexico formed but were completely overridden his laboratory examination and interpreta- locations: New Mexico Department of Agriculture, Las Cruces, 190 pp. by younger rock glaciers during the later tion of the soil samples. The manuscript Martin, W. C., 1964, Some aspects of the natural periglacial episode; or (3) they were gen- greatly benefited from the critical review history of Capitan and Jicarilla Mountains, erated during the earlier periglacial and comments of Paul A. Catacosinos, and Sierra Blanca Peak region of New Mex- episode, became inactive when less severe David W. Love, John D. Vitek, and Sidney ico; in Ash, S. R., and Davis, L. V. (eds.), conditions prevailed, and were reactivat- E. White. Support for the early stages of Ruidoso country: New Mexico Geological ed during the later episode. Because aplite the field investigation was provided by Society, Guidebook 15, pp. 171–176. and granophyre are more susceptible to the Geological Society of America research McLemore, V. T., and Allen, M. S., 1991, freeze-thaw action than porphyry, it is grant 1239-69. Geology of mineralization and associated probable that rock glaciers developed in alteration in the Capitan Mountains, Lincoln the western part of the range when older References County, New Mexico; in Barker, J. M., Kues, B. forms were being generated in the east. S., Austin, G. S., and Lucas, S. G. (eds.), Geology of the Sierra Blanca, Sacramento, No younger rock glaciers either situated Allen, B. D., 1991, Effects of climatic change on Estancia Valley, New Mexico: sedimentation and Capitan ranges, New Mexico: New up valley from or overriding the heads of and landscape evolution in a closed-drainage Mexico Geological Society, Guidebook 42, pp. older forms were observed either in the basin; in Julian, B., and Zidek, J. (eds.), Field 291–298. field or on aerial photographs in the west- guide to geologic excursions in New Mexico Morris, S. E., 1981, Topoclimatic factors and the ern part of the range. If older rock glaciers and adjacent areas of Texas and Colorado: development of rock-glacier facies, Sangre de exist in the west, they are completely cov- New Mexico Bureau of Mines and Mineral Cristo Mountains, southern Colorado: Arctic ered by younger forms, which seems Resources, Bulletin 137, pp. 166–171. and Alpine Research, v. 13, pp. 329–338. unlikely if the earlier periglacial episode Allen, B. D., and Anderson, R. Y., 1993, Evi- Péwé, T. L., 1983, The periglacial environment was more severe and/or of longer dura- dence for rapid shifts in climate during the in North America during Wisconsin time; in tion than the later episode. last glacial maximum: Science, v. 260, pp. Porter, S. C. (ed.), Late Quaternary environ- 1920–1923. ment of the United States, v. 1, The late Allen, M. S., and McLemore, V. T., 1991, The Pleistocene: University of Minnesota Press, Conclusions geology and petrogenesis of the Capitan plu- Minneapolis, pp. 157–189. ton, New Mexico; in Barker, J. M., Kues, B. S., Richmond, G. M., 1963, Correlation of some Physiographic criteria and soil develop- Austin, G. S., and Lucas, S. G. (eds.), Geology glacial deposits in New Mexico: U.S. ment may be used to distinguish rock of the Sierra Blanca, Sacramento, and Capitan Geological Survey, Professional paper 450-E, glaciers of two ages in the Capitan ranges, New Mexico: New Mexico Geo- pp. E121–E125. Mountains. Physiographic expression and logical Society, Guidebook 42, pp. 115–127. Richmond, G. M., 1986, Stratigraphy and corre- soil development suggest a late Wisconsin Bachhuber, F. W., 1989, The occurrence and lation of glacial deposits of the Rocky age and indicate two periglacial episodes paleolimnologic significance of cutthroat Mountains, the Colorado Plateau, and the

64 August 1999 New Mexico Geology ranges of the Great Basin; in Sibrava, V., tions of a packrat midden sequence from the Geographic Names Bowen, D. Q., and Richmond, G. M. (eds.), Sacramento Mountains, south-central New Quaternary glaciation in the northern hemi- Mexico: Quaternary Research, v. 22, pp. U. S. Board on Geographic Names sphere: Pergamon Press, New York, pp. 344–360. 99–127. Wahrhaftig, C. A., and Cox, A. W., 1959, Rock South Sandia Spring—spring, in Cibola Shroba, R. R., 1977, Soil development in glaciers in the Alaska Range: Geological National Forest/Sandia Mountain Quaternary tills, rock glacier deposits, and Society of America, Bulletin, v. 70, pp. Wilderness, 2.4 km (1.5 mi) south of taluses, southern and central Rocky 383–436. South Sandia Peak, 1.1 km (0.7 mi) east Mountains: Unpublished PhD dissertation, Washburn, A. L., 1980, Geocryology: A survey of Three Gun Spring, 4 km (2.5 mi) University of Colorado, Boulder, 424 pp. of periglacial processes and environments: northwest of Tijeras; Sandovol County, Shroba, R. R., 1991, Major trends in soil devel- John Wiley and Sons, New York, 406 pp. NM; sec. 8 T10N R5E, NMPM; opment and soil-clay mineralogy in late White, S. E., 1981, Alpine mass movement 35°05’56”N, 106°25’32”W; USGS map, Quaternary surficial deposits at Sierra Blanca forms (noncatastrophic): Classification, Tijeras 1:24,000. Peak, south-central New Mexico (abs.): description, and significance: Arctic and Geological Society of America, Abstracts with Alpine Research, v. 13, pp. 127–137. Steins Peak—summit, elevation 1,786 m Programs, v. 23, no. 4, p. 94. (5,861 ft), on the south side of Doubtful Tuan, Y. F., Everard, C. E., and Widdison, J. G., Canyon, 12.5 km (7.8 mi) north–north- 1969, The climate of New Mexico: New west of Steins, 0.8 km (0.5 mi) east of the Mexico State Planning Office, Santa Fe, 197 Arizona State boundary; named for pp. Major Enoch Steen (1800–1880); Hidalgo Van Devender, T. R., Betancourt, J. L., and County, NM; sec. 6 T23S R21W, NMPM; Wimberly, M., 1984, Biogeographic implica- 32°20’01”N, 109°02’ 35”W; USGS map, Doubtful Canyon 1:24,000; not Steens Peak. Bald Knoll Tank—reservoir, 38 m (125 ft) by 30 m (100 ft), in Gila National Forest, along the west slope of the Big Burro Mountains, 1.9 km (1.2 mi) northeast of Joe Harris Spring, 4 km (2.5 mi) north- west of Bullard Peak; Grant County, NM; sec. 23 T18S R17W, Gila and Salt River Meridian; 32°43’29”N, 108°34’ 25”W; USGS map, Bullard Peak 1:24,000; not Bold Tank. Burnt Mill Canyon—valley, 3.2 km (2 mi) long, in Cibola National Forest, heads at 35°11’26”N, 108°25’13”W, trends south- west to a point 6.3 km (3.9 mi) northeast of the community of Ramah, 6.4 km (4 mi) north of Wild Sheep Mesa; Cibola County, NM; secs. 20, 17, 16, 9 & 10 T11N R15W, NMPM; 35°10’17”N, 108°26’ 35”W; USGS map, Ramah 1:24,000; not Oak Hollow. Kelly Tank—reservoir, 61 m (200 ft) by 53 m (175 ft), in Gila National Forest, between Park Canyon and Burro Spring Canyon, 8 km (5 mi) south–southwest of Bullard Peak; Grant County, NM; sec. 23 T19S R17W, Gila and Salt River Meridian; 32°38’20”N, 108°34’16”W; USGS map, Bullard Peak 1:24,000; not Burro Spring Tank. Oak Hollow—valley, 4 km (2.5 mi) long, in Cibola National Forest, heads at 35°11’44”N, 108°23’04”W, trends south- west to a point 8 km (5 mi) northeast of the community of Ramah; Cibola County, NM; secs. 14, 15 & 22 T11N R15W, NMPM; 35°10’05”N, 108°24’ 55”W; USGS map, Ramah 1:24,000. Richardson Tank—reservoir, 53 m (175 ft) by 30 m (100 ft), in Gila National Forest, along Burro Spring Canyon, 8.9 km (5.5 mi) south–southwest of Bullard Peak; Grant County, NM; sec. 23 T19S R17W, Gila and Salt River Meridian; 32°38’ 04”N, 108°34’14”W; USGS map, Bullard Peak 1:24,000; not Richard Tank. —David McCraw NMBMMR Correspondent

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