E. W. Hilgard— Geology of the Delta. 



sodium and magnesium orig-inally 

 relatively increased : and this airai 



■ proportion between these base- 

 irenient of sulphate of magnesiui 

 change not readily explained. 



the shelf of " blue clay bottom " ext. 

 .\L.\\t depth below the sea-level, aii'i 

 into the Gulf Tt is upon this ini] 



dated tor a <jr.-;u Icnn'th of time, unless the water bf 

 oft'orthron-i it bv -ome means! 



The bar. in it. annual advance of about 338 feet ^ 

 over this liquid mud stratum, exertimr a inv.-nn^ muo 

 than that of the sea ; and were it restiiiL- <>n a i^^^i-viou- 

 the liquid mud would doubtless soon b<> ( oi,-)l!d;!t' 

 sheet of clay. As it is, the tendonrv v,-dl b<' to -■ 

 from under the crest of the bar. both" -.Mwar-I and 1 



