See more from this Division: Topical Sessions
See more from this Session: Lakes in Extreme Environments: Earth and Beyond
Abstract:
A comparison of preliminary 14C dates and available lake level reconstructions reveals that the stromatolites started forming at water depths of 30 meters or more and continued to grow as lake level fell between 2800 and 2000 B.P. Accretion rate slowed as lake depth shallowed. A detailed study of growth direction was undertaken by sampling stromatolites that were encrusting all exposed sides of an in situ boulder located on the northwest side of Walker Lake. Samples were taken from the north, south, east, and west sides of the boulder, both from the steep (>75 degree) sides and from the top. Though incident light would have been most intense at the top of the boulder, the stromatolites show no evidence of growth towards a light source; rather, most of the stromatolites display surface normal growth. While this evidence does not rule out a biological origin for the structures, it does indicate that these particular stromatolites were not formed in response to incident light, and it is not clear how trapping and binding would produce laminae with the orientations noted here.
See more from this Division: Topical Sessions
See more from this Session: Lakes in Extreme Environments: Earth and Beyond