Pleistocene algal pinnacles at Searles Lake, California

摘要: ABSTRACT Searles Lake is a playa or dry lake which occupies the central floor of Basin, northwardtrending graben Basin and Range province in southeastern California. During pluvial periods Pleistocene epoch deep-water lakes filled two these more than 500 pinnacled masses calcareous tufa accumulated an arm-like bay at southwest end basin. Pinnacles are tower-, tombstone-, cone-shaped large limestone ridges. Most pinnacles 10 to 40 ft high, but few reach heights between 100 140 ft. Basal diameters widths range from about as much average 20 30 Seven varieties compose pinnacles; one also found lenticular bodies buried lacustrine sediments underlying northern bay. It proposed that were precipitated by algae orifices sublacustrine springs issuing along faults striking N. 65° W., 50° 30° E., 55° E. basement rocks. Deposition took place Tahoe age 32,000 years ago. midway formed Tioga initially flooded 23,000 ago lasted until 10,000 its maximum stand was approximately 460 deep highest stage surface reached elevation 2000