Geology . ^s^kji. Fig. 545.—Tufa deposits in the basin of Lake Lahontan. (Russell, U. S. Geol. Surv.) oldest tufaceous deposits lined the basin of the lake at the time of itsfirst expansion; the next were made when the lake was low, between THE PLEISTOCENE OR GLACIAL PERIOD. 465 the two stages of expansion; and the youngest were made at the timeof the last expansion. Oolite was deposited at some stages of thelakes history, and is now making about Pyramid Lake. In some partsof the Lahontan basin there are deposits of salt, and salt is also derivedfrom brine wells. Subsequent to the last stage o
Geology . ^s^kji. Fig. 545.—Tufa deposits in the basin of Lake Lahontan. (Russell, U. S. Geol. Surv.) oldest tufaceous deposits lined the basin of the lake at the time of itsfirst expansion; the next were made when the lake was low, between THE PLEISTOCENE OR GLACIAL PERIOD. 465 the two stages of expansion; and the youngest were made at the timeof the last expansion. Oolite was deposited at some stages of thelakes history, and is now making about Pyramid Lake. In some partsof the Lahontan basin there are deposits of salt, and salt is also derivedfrom brine wells. Subsequent to the last stage of expansion, the waters appear tohave been completely dried up. The period of maximum desiccationis thought to have been no more than 300 years ago. Since then thehumidity of the region has so far increased as to develop small lakesin the deeper parts of the former basin. All lines of evidence point to the shortness of the time since LakesBonneville and Lahontan existed. The embankments of sediment
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