Geology of Walker Lake

by Willow Phillips

   80 million years ago the huge Sierra Nevada granite batholiths pushed its way upward creating the Wassuk Range. The first fault along this mountain range was called the Pine Nut Fault. Most of this fault lies beneath the alluvial fans of the valleys and under Walker Lake. Next came the present day fault system known as the Walker Lane Fault system. Without these two faults and the depression left behind, there would be no Walker Lake.

   Lake Lahontan was the first lake in this area, which covered most of north central Nevada. Many of the benchmarks of Lake Lahontan can be seen as you drive to Fallon. When this huge lake dried up the lakes we have today, Walker and Pyramid were left.

   Why did the huge lake dry up? During the ice ages the jet stream of winds carried moisture off the glaciers and into Nevada. As these glaciers moved northward, less moisture came into the area. The rise of the Sierra Nevada’s prevented the flow of moisture coming from the ocean, which stopped the clouds from forming.

   The highest peak in the Wassuk Range is Mount Grant at 11,239 feet. It is asymmetrical with steep slopes on the north side and long sloping sides to the west. The granites rocks that compose most of this range are grey to yellow orange. The yellow orange shows the presents of iron oxide. At the top of the mountain there is a present of limestone, which was probably pushed up with the mountain.

   Along the western edge of Walker Lake, across from 20-mile beach, can be found Tufa—limestone or calcium carbonate that precipitates when it comes in contact with an alkaline lake. If you walk along part of the old road, you can see the white/grey tufa and how some of the round rocks have been cemented together. 

   Walker Lake has a puzzling past. When the USGS drilled the lake, they expected to find a huge amount of sediment, as one would find in old lakes, however, they found very little. The theory is that Walker Lake experienced dry periods unrelated to the climate. A fault movement caused the Walker River to flow into the Carson Desert. In time the river re-established its normal flow once again into the lake. When the lake was dry the strong winds blew away the dried up sediment.

   As early as 1870, the minerals in Mt. Grant District or Walker Lake District produced a minor amount of gold and silver from quartz veins in the granite rocks. The main mine was the Big Indian Mine, and its equipment can be found at the Mineral County Museum, in Hawthorne. Smaller amounts of gold were taken out of Cory Canyon, and a canyon at the Barlow Ranch.

   Bentinite clay is found on the base and is used to keep water from leaking into the ground.

   Copper was found and produced at Cat Creek in 1920's. The ore was found in a brecciated fault zone, where disseminated pyrite and chalcopyrite.

   There are small claims on the northwest side of the mountain that are being worked—so please stay away!

   The mountains on the north side of the lake are called the Gillis Range. These mountains are made up of limestone with granite intrusions, with a layer of volcanic on top. In some locations the once flat limestone is standing on edge or vertical. A drive up Ryan Canyon will let you view rocks that have been stained as the minerals moved through.