E. T. DUMBLE—SOURCES OE THE TEXAS DRIFT. 
13 
It is as yet too early to speak decidedly of the period at which the 
drift was formed, or of the causes which took part in its formation and 
distribution. Of one thing we are sure: we have here no direct glacial 
action, though we may have an indirect result, caused by the melting 
of the waters of the glaciers, or snow fall accompanying them, or per¬ 
haps the overflowing of the Pliocene lakes; the rushing of waters to 
the lower ground occupied by the gulf, and the consequent distribution 
of the materials of the drift. The consideration of the subsequent re¬ 
arrangement and modification of the materials by the waters of the 
gulf and fluviatile action must also be deferred until a closer study is 
made of them. 
