Lake Harper

Coordinates: 35°00′N 117°15′W / 35.000°N 117.250°W / 35.000; -117.250[1] Lake Harper is a dry lake in California.

General

Lake Harper during its highstand reached an elevation of 658 metres (2,159 ft) above sea level,[2] had a surface area of 255 square kilometres (98 sq mi)[1] and was inhabited by cyprinid minnow,[2] molluscs and ostracods.[1] Ostracods found in Lake Harper are species of Candona, Cypridopsis, Heterocypris and Limnocythere.[3] These species indicate a freshwater lake with seasonal inflow and some shallower environments.[4] An elongated peninsula jutted into the lake from the western shore and smaller peninsulas existed on the northern and southern shores towards the eastern side of the lake. Blue clays in boreholes and fine grained mud and sand on the former shores testify to the existence of a lake there.[2]

General hydrology

Other lakes nourished by the Mojave River are Lake Manix, the Cronese Lakes, Lake Mojave in the present day Soda Lake and Silver Lake basins and Lake Manly in present-day Death Valley; presently the river ends in Soda Lake after 200 square kilometres (77 sq mi). The formation of these pluvial lakes depends on the southward shift of the polar jet stream during the ice ages.[5]

History

The highest shorelines are dated to 24,400 ± 2,190 and 25,000 ± 310 radiocarbon years ago;[1] further dates are 40,460 ± 550 and 33,830 ± 340 calibrated radiocarbon years ago.[3] Lake Harper was the terminal lake for the Mojave River between 40,000 and 45,000 years before present,[5] which is also considered to be the time of highstand of the lake;[4] the river alternatively discharged into this lake and into Lake Manix farther downstream.[1] The timespan where the Mojave River flowed into Harper Lake began 575,000 - 475,000 years ago when the river escaped the Victorville area and entered Harper Lake until 500,000 years ago when it started alternating between Lake Manix and Lake Harper.[2] The last time that the Mojave River reached Lake Harper was between 25,000 and 20,000 years before present,[6] but this finding was later considered to be doubtful.[4]

Presently Lake Harper forms a playa at an elevation of 615 metres (2,018 ft) above sea level. It features a dry climate with desert scrub vegetation surrounding the lake bed.[1] Neogene alluvial fans form much of the surrounding and overlie older basalts.[2]

References

  1. 1 2 3 4 5 6 Garcia et al. 2014, p. 306.
  2. 1 2 3 4 5 Garcia et al. 2014, p. 307.
  3. 1 2 Garcia et al. 2014, p. 310.
  4. 1 2 3 Garcia et al. 2014, p. 313.
  5. 1 2 Garcia et al. 2014, p. 305.
  6. ↑ Garcia et al. 2014, p. 308.

Sources

  • Garcia, Anna L.; Knott, Jeffrey R.; Mahan, Shannon A.; Bright, Jordon (2014-03-01). "Geochronology and paleoenvironment of pluvial Harper Lake, Mojave Desert, California, USA". Quaternary Research. 81 (2): 305–317. doi:10.1016/j.yqres.2013.10.008.
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