Eetza, A Geologic Formation

Our consulting firm is named after the geologic Eetza Formation from the sediments deposited by Pleistocene Lake Lahontan in the Carson Desert near Fallon, NV.  This interglacial lake at some point covered most of the Great Basin. According to Shackleton and Opdyke (1973) these deposits could date from 180,000 to about 130,000 years ago.

Morrison (1961a and 1964a) divided the sediments deposited by this lake into six formations and called them the Lahontan Valley Group.  The Eetza’s formation at the bottom is the oldest and records the first deep-lake period.  Eetza is followed by the Wyemaha and Sehoo Formations of younger age.  The latter records the second deep-lake period of Lake Lahontan. It was during this period that human archaeological evidence is first found.  The single projectile point discovered in place in upper lacustrine clay by McGee (1889) is apparently of middle Sehoo age. A small nomadic Indian population occupied the area during late Sehoo lake time, judging from the archaeological record in Hidden Cave (Grosscup, 1956; Morrison, 1958).  The four projectile points found in Hidden Cave are unlike any points previously reported for the Humboldt Sink and Carson Desert areas, but resemble some from Dixie Valley, NV from the lowest level of Etna Cave, NV, and from northeastern California (by Horacio Ferriz Ph.D).