The huge valley covering about 590 square miles (1,500 km2)[1] is a down-faulted basin, formerly a lake of similar geologic origin to Lake Tahoe to the south, now filled with sediment up to two thousand feet thick.
[3] The extensive marshes are filled with cattails, bulrushes and alkaline flats that drain into the Middle Fork Feather River.
A Biological Baseline Study of Sierra Valley Marsh, California 1976.
This was a student originated study funded by the National Science Foundation to assess biological resources of the high-altitude freshwater marsh in Sierra Valley.
A Biological Baseline Study of The Sierra Valley Marsh California - 1976