48 



BULLETIN 61, U. S. DEPAETMENT OF AGEICULTTJKE. 



able beds of salines than marshes of the first type. Descriptions of Searles and 

 Columbus Marshes, Railroad and Dixie Valleys, Sand Springs Flat, and Sevier Lake 

 follow. 



SEARLES MARSH. 



Searles Marsh lies in the northwestern part of San Bernardino County, Cal., about 

 30 miles northeast of Randsburg. It lies in a drainage basin of 4,850 square miles 

 area. 0. E. Dolbear states that the area of the central depression is about 62.5 square 

 miles. This would give a ratio of 77.6 square miles of basin area to 1 square mile of 

 central depression area. The lowest part of the depression is 12 square miles in area, 

 and is occupied by a smooth, hard floor of salt (PI. Ill, fig. 2). Portions of the 

 area are covered by debris; other portions by efflorescences and crusts from a fraction 

 of an inch to several feet in thickness; and other portions are covered with clay muds 

 which are in part dried out and firm and in part are soft. Plate IV, figure 1, shows a 

 trona reef in the northeastern part of the marsh. De Groot ^ reports results of a 

 boring and shows a section of the marsh. Dolbear ^ quotes the results of two bores, 

 one in the central salt area and the other in the marginal area outside of the salt bed. 



Section of Searles Marsh (De Groot). 

 Depth. 



2 feet Salt and thenardite. 



4 feet Clay and volcanic sand with some hanksite. 



8 feet Volcanic sand and black clay with bunches of trona. 



8 feet Volcanic sand containing glauberite, thenardite, and a few crystals of 



hanksite. 



20 feet Mud smelling of hydrogen sulphide and containing layers of glauberite, 



soda, and hanksite. 



28 feet Solid trona overlain by a thin layer of very hard material. 



230+feet Clay, mixed with volcanic sand and permeated with hydrogen 



sulphide. 



Analyses of samples from borings in Searles Lake. 



[Analyses by Dolbear.] 



Depth. 



Insol. 



NaCl. 



Na2SO<. 



NatCOj. 



NaHCOs. 



Na2B407. 



H2O. 



Feet. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



0-18 



0.2 



79.7 



7.6 



3.2 



0.0 



Tr. 



3.3 



18-25 



1.4 



44.0 



30.5 



14.8 



2.5 



1.0 



5.8 



25^0 



1.4 



47.3 



28.1 



10.6 



.0 



2.0 



10.6 



30-35 



3.0 



42.7 



17.1 



19.1 



5.9 



2.0 



10.2 



35-50 



1.4 



43.5 



22.3 



■ 9.5 



2.5 



5.5 



15.3 



50-65 



Tr. 



82.8 



10.6 



3.2 



.8 



Tr. 



2.6 



65-79 



Tr. 



19.0 



7.3 



40.3 



18.5 



.5 



14.4 



Analyses of samples from borings outside of salt-bed area. 



[Analyses by Dolbear.] 



Depth. 



Insol. 



NaCl. 



NaaSOi. 



NazCOs. 



NaHCOg. 



Na2B407. 



H2O. 



Feet. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



P.ct. 



0-13 

 13-20 



Mud. 

 8.3 















66.8 



1.0 



11.7 



5.6 



0.4 



6.8 



20-25 



Tr. 



98.4 



.8 



1.8 



.0 



.0 



.0 



25-30 



1.4 



15.3 



4.7 



38.7 



24.4 



Tr. 



15.5 



30-35 



15.0 



39.6 



2.3 



16.4 



3.4 



5.56 



12.74 



35-40 



33.4 



17.5 



3.9 



14.85 



4.7 



5.6 



20.05 



40-45 



36.0 



9.8 



2.9 



12.5 



.4 



6.57 



26.28 



45-50 



32.5 



9.0 



2.6 



21.2 



3.8 



.0 



30.9 



50-53 



30.7 



8.3 



2.8 



23.3 



7.6 



Tr. 



27.8 



53-55 



31.0 



9.0 



2.8 



21.2 



10.9 



.0 



25.1 



55-60 



26.9 



5.8 



1.9 



26.5 



14.3 



Tr. 



24.6 



00-65 



3.2 



4.5 



38.0 



28.6 



10.1 



Tr. 



10.6 



65-70 



6.8 



5.1 



6.8 



43.5 



21.0 



Tr. 



16.8 



70-75 



7.6 



4.0 



2.8 



53.0 



16.0 



.0 



16.6 



1 10th Annual Report, California State Mining Bureau, p. 535. 



2 Engineering and Mining Journal, Feb. 1, 1913, p. 260. 



