Lake San Agustín

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Coordinates: 33°49′N 108°11′W / 33.82°N 108.19°W / 33.82; -108.19[1]
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Lake San Agustín
Satellite image of the northern basin
Lake San Agustín is located in New Mexico
Lake San Agustín
Lake San Agustín
Coordinates33°49′N 108°11′W / 33.82°N 108.19°W / 33.82; -108.19[1]

Lake San Agustín is a

highstands it covered an area of 1,200 square kilometres (460 sq mi) with a maximum depth of 70 metres (230 ft), and split into several separate lakes while drying out. The lake last appeared during the last glacial maximum (LGM) and dried out at the beginning of the Holocene
, with the last remnant disappearing about 5,000 years ago.

The lake may have been an important resource for local

core samples
taken from its bed have been used to reconstruct the past vegetation of New Mexico.

Description

The area of the former lake is now part of

radiotelescopes are situated on the floor of the northeastern basin.[4] Datil and Horse Springs are located north of it. State Road 12 runs along part of its northwestern shore, and U.S. Route 60 crosses over the northeastern lake bed.[5]

Three lake basins, connected by channels, lie on the floor of the former lake; these are C-N Lake at 2,101 metres (6,893 ft) elevation, San Agustin Lake at 2,065 metres (6,775 ft), and White Lake at 2,119 metres (6,952 ft).

closed; groundwater outflow appears to occur.[7]

Former state

At

freshwater lake,[11] but salinity varied by seasons[12] and on average, alkaline waters may have been more common.[13] The freshness of its waters may indicate that it overflowed (which would prevent salts from accumulating)[11] but there is no geomorphological evidence of an overflow.[14]

The former lake left

wave-cut notches.[16] The shores of the former lake included numerous bays, which developed bars and spits.[18] Alluvial fans from the Mogollon Slope drained into the lake;[19] the shorelines are cut into the fans[20] and their further development after the lake dried up is feeble.[21]

Watershed map

Its

Continental Divide-Mangas Mountain-Tularosa Mountain, Continental Divide-Elk Mountains-O Bar O Mountain-Pelona Mountain-Luera Mountains and San Mateo Mountains.[2] None of these mountains were glaciated during the Pleistocene;[24] today they are remote and largely devoid of surface water.[25]

Flora and fauna

Lake sediments contain remnants of

gastropods and ostracods.[26][27] Pine-spruce woodlands and sagebrush grew along the shore and surroundings of Lake San Agustín.[28] The fauna that lived around the lake share characteristics with present-day populations that occur at higher elevations and/or farther north.[29]

Animal fossils found in lake deposits include unidentified species,[30] but also fish and:[31]

History

Based on a 300 metres (980 ft) long

core drilled into the floor of the basin, sedimentation goes back to the Pliocene but was variable over time.[5] It is the only basin in the region where the Neogene infill has been probed by coring.[37]

Lakes may have existed for 650,000 years in the Plains of San Agustín

Dansgaard-Oeschger cycles in Greenland.[40] Individual highstands at Lake San Agustín 22,000, 19,000, 17,000 and 16,000 years ago are correlated to contemporaneous highstands of Lake Estancia and Lake King in Texas, as well as Lake Lisan in the Near East.[41] During the last glacial maximum highstand, moisture influx was more than four times larger than present-day moisture supply[42] and until 13,000 years ago precipitation primarily fell during winter.[43]

By around 13,200 years ago, water levels had dropped beneath the 2,105 metres (6,906 ft) elevation

BCE.[49] Presently, there is no permanent water body in the Plains of San Agustín, but ephemeral lakes sometimes form after wet years.[15]

Lake San Agustín is one of many pluvial lakes in the wider region[2] of Arizona, California, Nevada and New Mexico.[50] During the ice age, the Laurentide Ice Sheet expanded and displaced the jet stream and its precipitation systems to the south; simultaneously the Atlantic Ocean cooled and the Pacific warmed, increasing moisture supply to the region of the present-day Southwestern United States.[51]

Archeology

Numerous

archeological sites have been found at the former lake, which provided important resources for early humans during the end of the ice age.[52] The Ake Site, an archeological site on the National Register of Historic Places,[53] is situated on the floor of the northeastern basin. Bat Cave faces the southwestern basin[5] and formed through wave-cut erosion by Lake San Agustín.[20] Folsom-age sites are mostly found in locations that suggest they were redeposited, or in association with aeolian deposits.[10]

Most sites are associated with the smaller basins, implying that human activity came towards the end of Lake San Agustín's existence when it was shrinking and the smaller basins had turned into marshes and ponds.[10] As water availability declined during the Holocene, occupation in the San Agustín area declined as well,[54] especially after the demise of the Horse Springs lake.[55] Early populations were hunters, later they experimented with agriculture.[25]

Various projects to manage the cultural heritage took place in the San Agustín area, of mostly limited spatial extent except for those associated with the Very Large Array. Some of them relied on projectile points from private collections.[56] According to an Ndé Apache creation myth, the creator Ussen warned her creation White Painted Woman of a large flood; White Painted Woman took refuge in an abalone shell and eventually became stranded on the San Agustín plains. White Painted Woman there gave rise to Child of the Water, the progenitor of the Ndé people.[57]

Present-day climate and vegetation

Present-day vegetation of the Plains of San Agustín

The region has a

Pacific weather systems in winter.[59] Thunderstorms during summer can cause floods that deposit sediments in the basin.[20]

Present-day vegetation consists of

white fir and the occasional spruce occur.[3]

Research history

Early reconnaissance was carried out by Kirk Bryan, with the results published in 1926.[60] Bryan was the first to identify the existence of a former lake and named it "Lake San Augustin".[14] In 1939 William E. Powers published a detailed study of the remnants of the former lake.[60] Early research considered the possibility of an earlier overspill to the Rio Grande or even to the Gila River.[61] Archeological surveys took place after World War II.[53] In the 1990s, fossils were found on the ground of the Very Large Array.[62]

Pollen deposits from the lake were used to reconstruct the vegetation of New Mexico during the LGM;[63] they show a vegetation of pine-spruce woodlands with frequent Artemisia.[26] Attempts to reconstruct the Pleistocene climate across several glacial cycles have all failed as of 2005,[64] and as of 2014 none of the shorelines have been dated.[44]

Geology

The valley the lake formed in is a tectonic

Rio Grande Rift,[16] which the graben may be part of.[66] Other interpretations are it is a basin formed by a circular emplacement of volcanic rocks, or a large volcanic caldera[67] which may be the source of the 33.7 million years old Horse Springs dacite[68] and Blue Canyon tuff.[69] There is no evidence of recent faulting[20] or of ongoing subsidence[70] and the shorelines lie at the same altitude over the entire basin.[14]

Apart from one Permian outcrop, all the rocks around the Plains of San Agustín are volcanic rocks of Eocene to Quaternary age[69] with compositions ranging from basalt to rhyolite.[71] West of the graben lies the dominating Horse Mountain volcano, which was active 14 million years ago, and there are other volcanic buttes in the vicinity.[5]

References

  1. ^ Shuman & Serravezza 2017, p. 63.
  2. ^ a b c Potter 1957, p. 114.
  3. ^ a b Markgraf et al. 1984, p. 337.
  4. ^ a b c d e f Parker, Tanaka & Senske 2002, p. 24.
  5. ^ a b c d e f Parker, Tanaka & Senske 2002, p. 25.
  6. ^ Hudson et al. 2023, p. 3.
  7. ^ a b c Lucas, Morgan & Zeigler 2005, p. 20.
  8. ^ Lucas & Sullivan 2015, p. 280.
  9. ^ Hudson et al. 2023, p. 17.
  10. ^ a b c d Lucas, Morgan & Zeigler 2005, p. 272.
  11. ^ a b Cole 1963, p. 405.
  12. ^ Markgraf et al. 1984, p. 341.
  13. ^ Foreman et al. 1959, p. 120.
  14. ^ a b c Powers 1933, p. 51.
  15. ^ a b c d e f g h Hill & Holliday 2011, p. 6.
  16. ^ a b c Lucas, Morgan & Zeigler 2005, p. 139.
  17. ^ Ratte 2001, p. 3.
  18. ^ Goman 2014, p. 7.
  19. ^ Berman 1979, p. 4.
  20. ^ a b c d e Potter 1957, p. 115.
  21. ^ Powers 1933, p. 52.
  22. ^ a b Lucas, Morgan & Zeigler 2005, p. 108.
  23. ^ Lucas, Morgan & Zeigler 2005, p. 177.
  24. ^ Pazzaglia 2004, p. 8.
  25. ^ a b Julyan 2006, p. 279.
  26. ^ a b Lucas, Morgan & Zeigler 2005, p. 172.
  27. ^ Lucas, Morgan & Zeigler 2005, p. 202.
  28. ^ Lucas & Sullivan 2015, p. 350.
  29. ^ Lucas & Sullivan 2015, p. 351.
  30. ^ Lucas & Sullivan 2015, p. 395.
  31. ^ a b Lucas, Morgan & Zeigler 2005, pp. 202, 222.
  32. ^ a b Lucas, Morgan & Zeigler 2005, pp. 202, 222, 242.
  33. ^ a b c Lucas & Sullivan 2015, p. 281.
  34. ^ Lucas & Sullivan 2015, p. 394.
  35. ^ Lucas & Sullivan 2015, p. 256.
  36. ^ Lucas, Morgan & Zeigler 2005, p. 222.
  37. ^ Lucas, Morgan & Zeigler 2005, p. 39.
  38. ^ Reineck & Singh 1980, p. 254.
  39. ^ Dello-Russo 2012, p. 56.
  40. ^ Wilkins & Currey 1997, p. 312.
  41. ^ Abu Ghazleh & Kempe 2009, p. 261.
  42. ^ Krider 1998, p. 287.
  43. ^ Dello-Russo 2012, p. 57.
  44. ^ a b Goman 2014, p. 15.
  45. ^ Hudson et al. 2023, p. 4.
  46. ^ Hudson et al. 2023, p. 22.
  47. ^ Hudson et al. 2023, p. 23.
  48. ^ Hill & Holliday 2011, p. 3.
  49. ^ Hurt 1953, p. 209.
  50. ^ Dean et al. 2006, p. 106.
  51. ^ Brook et al. 2006, p. 502.
  52. ^ Lucas, Morgan & Zeigler 2005, p. 263.
  53. ^ a b Berman 1979, p. 8.
  54. ^ Hill & Holliday 2011, p. 15.
  55. ^ Hill & Holliday 2011, p. 17.
  56. ^ Hill & Holliday 2011, pp. 6–7.
  57. ^ Babcock 2016, pp. 23–24.
  58. ^ Markgraf et al. 1984, pp. 337–338.
  59. ^ Goman 2014, p. 2.
  60. ^ a b Lucas, Morgan & Zeigler 2005, p. 35.
  61. ^ Blackwelder 1948, p. 117.
  62. ^ Lucas, Morgan & Zeigler 2005, p. 201.
  63. ^ Lucas, Morgan & Zeigler 2005, p. 179.
  64. ^ Lucas, Morgan & Zeigler 2005, p. 112.
  65. ^ Hill & Holliday 2011, p. 4.
  66. ^ Blanchard 1982, p. 31.
  67. ^ Berman 1979, pp. 4–5.
  68. ^ Ratte et al. 1994, p. 1.
  69. ^ a b Ratte 2001, p. 1.
  70. ^ Ratte 2001, p. 2.
  71. ^ Foreman et al. 1959, p. 117.

Sources

External links
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