658 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



Miles 









\ x 







^ 





\ 



■3000 



5000 



600 



.7000 



9000 



Fig. 41.7. Cross section through the Jackson dome, Mississippi, taken from west to east. After McGloth- 

 lin, 1944. 



Another structure in the Mississippi embayment is the Desha basin 

 north of the Monroe uplift. It is not a closed basin but opens on the 

 east into the broad embayment. In southwestern Alabama is the Hatche- 

 tigbee anticline which trends to the northwest and has surface out- 

 crop expression. 



Salt Domes 



Distribution. Semicylindrical masses of salt have thrust their way 

 upward in the poorly consolidated sediments of the Gulf Coastal Plain 



in a variety of forms. They are known as salt domes or salt plugs, 

 characteristically from one-half to two miles in diameter, and are the 

 loci of many fine oil fields. Over 200 are now known in the Gulf Coast. 

 They are distributed in two general groups: (1) the coastal domes prin- 

 cipally through southern Texas, the Mississippi delta of Louisiana, and 

 the shallow offshore shelf (Figs. 41.1 and 41.8); and (2) the interior 

 domes. Some coastal domes also occur in northern Mexico in the Vera 

 Cruz-Tabasco basin. The black dots on Fig. 41.9 indicate the salt domes 

 discovered to date. It will be seen that the greatest number are in the 



