307 



Fig. .•{.—Mm. (.f cMslcrii X.irth Am.Tica Hliowing the grcatof 

 of Mexican onibayinciit ( Lcbanoii-l'aiiHilia time) and tin; prob: 

 tions of the Appalachian and Chaniplain troughs. 



t CXtl'llt of till 



