PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



THE GEOLOGICAL SOCIETY OF WASHINGTON 



The 292d meeting was held in the lecture room of the Cosmos Club, 

 on February 24, 1915. 



INFORMAL COMMUNICATIONS 



M. R. Campbell, Movement of sand-dunes on the California coast. 

 The dunes described occur near Monterey. Ordinarily they are 

 not in motion, but are covered with a growth of chaparral, and the 

 impression first produced was that their present stationary condition 

 might denote a change of climate since their formation. Later it 

 was observed that occasional breaches are formed, from which the 

 sand is swept forward in long tongues. After a certain period movement 

 at such a location ceases and the newly formed dunes become covered 

 with chaparral. Thus movement is occurring only here and there 

 at any one time, but after a certain period the material of the whole 

 dune has become shifted. 



Discussion: A. C. Spencer inquired as to the cause of the primary 

 breach. Campbell believed this might be due to a severe storm or 

 an extraordinary wind. 



REGULAR PROGRAM 



C. J. Hares: Correlation of sotne of the Cretaceous and Eocene 

 formations of Central Wyoming. The uniformity of the Cretaceous 

 formations over much of Wyoming indicates that sedimentation was 

 unobstructed and that the present mountain chains contributed 

 little, if any, of those sediments. The Cretaceous sediments were 

 probably derived in great part from farther west. The mountains 

 rose later, though movement was probably initiated in late Cretaceous. 



The best comparison of these formations may be obtained by using 

 the Niobrara as a datum plane. The Niobrara is composed of 200 

 to 1,700 feet of calcareous shale and limestone, bearing the distinctive 

 Ostrea congesta fauna, and marks the maximum extension of deep ma- 

 rine water. The Niobrara is succeeded in Natrona County by 2000 

 to 3000 feet of dark, marine shale, which is equivalent to the Steele 

 shale of Carbon County. The Steele and underlying formations, 

 except for a narrow outcrop of a White River formation, are continuous 

 from Carbon to Natrona County, but the overlying formations have 

 been eroded. The Steele formation in Carbon County is overlain 



328 



