1914] Buwalda: Pleistocene Beds in the Mohave Desert 457 



sands. The writer has termed these deposits the Manix Beds, and 

 has referred to the lake as Manix Lake. Fossil remains of six 

 species of mammals, of several birds, molluscs, and fish were 

 obtained from the lake-beds. The mammals indicate a Pleisto- 

 cene age for the formation, but with out present knowledge it 

 is not possible to determine definitely the particular stage of 

 Pleistocene time. Deformation of the region occurred not long 

 before the origin of the lake, and to a less extent after the lake's 

 extinction. No evidence was noted indicating disturbance in 

 very recent times. It is evident that the lake owed its origin to 

 changes of climate in the direction of greater precipitation over 

 large areas and to deformation in this or adjoining regions. The 

 disappearance of the lake was the joint result of the partial 

 filling of its basin with sediments and the downcutting of its 

 outlet. The evidence obtained indicates that the climate in this 

 region and in that to the west has become more arid since the 

 deposition of the Manix Lake Beds in Pleistocene time. 



Transmitted June 9, 1913. 



