ABSTRACTS AND DISCUSSIONS OF PAPERS 71 



tions are included in the Laramie. The Beckwith has been assigned to the 

 Cretaceous or Jurassic and the Bear River to the Upper Cretaceous. 



There is a considerable lack of agreement, both lithologically and faunally, 

 between the formations in the quadrangles named and the Beckwith and Bear 

 River formations in their type localities. The discrepancy is so great that it 

 now seems inadvisable to continue the use of the names Beckwith and Bear 

 River in the district discussed. Three groups of strata are recognized, the 

 lowest of which is marine Jurassic, and rests unconformably on the Twin 

 Creek limestone, the main Jurassic formation of the region. The two higher 

 groups are non-marine and probably Lower Cretaceous. They are separated 

 from each other by an unconformity, but the lower group appears to be con- 

 formable on the Jurassic beds below. The two higher groups have some re- 

 semblances to the Kootenai of Montana and Canada, but the data are at 

 present insufficient for their correlation with that formation. No character- 

 istic Bear River fossils have been found in the district, though such have been 

 found farther north, and there is a possibility that the doubtful beds may 

 grade upward into the true Bear River in that direction. 



The beds formerly called Beckwith are divided into seven formations and 

 a new name is given to the strata hitherto called Bear River. The paper 

 gave a statement of the stratigraphic problems involved, together with a de- 

 scription of the formations. 



Presented in abstract extemporaneously by the senior author. 



SEDIMENTATION ALONG THE GULF COAST OF THE UNITED STATES 



BY E. W. SHAW 



(Abstract) 



Sedimentation along the Gulf Coast of the United States proceeds in three 

 general and markedly different ways, each of which prevails over a large area. 

 On the west coast the sediment delivered to the sea by streams is being re- 

 worked, some of it many times over, but is not carried far away. At the 

 mouths of the Mississippi silt, clay, and fine sand are accumulating, layer on 

 layer, almost precisely where dropped by the river. Along the Florida coast 

 comparatively little sediment is carried into the sea by streams, and the littoral 

 deposits consist largely of very clean sand and calcium carbonate extracted 

 from sea-water by invertebrates, alga?, bacteria, etcetera. 



The lagoon and barrier beach conditions which prevail along the west coast 

 and a part of the north coast are perhaps the most common, and those at the 

 mouths of the Mississippi most unique, though the processes in operation at 

 the southern end of Florida differ in some respects from any in operation 

 elsewhere in the world. 



The object of the paper was to compare and contrast individual processes 

 and results affecting each region. On shore and off shore samples of sediment 

 from each of the three general regions were exhibited. 



Presented in abstract extemporaneously. 



