THE APPALACHIAN FOLDS 807 



The trend of the Appalachian folds. 



The Appalachians furnish a good example of an extended line of 

 folding formed at approximately the same time, i. e., the end of 

 the Palaeozoic. They show a remarkable series of curves of varying 

 size, which, with reference to the land, may be called convex or 

 land lobes, when they bulge seaward, and concave or sea lobes, 

 when they extend back into the land. (See the map, Fig. 192.) 

 Beginning in the southwest, we have the following : 



a 







-^E^C 



Fig. 191. Diagrams showing the steps by which complexly folded strata are 

 produced. A — C, deposition, folding and truncation of first series ; 

 D — F, deposition, folding and erosion of second series, the fold- 

 ing and erosion also affecting the first series. 



1. Louisiana sea lobe, extending from Texas to central Mis- 

 sissippi with the apex near Little Rock, Arkansas, and with proba- 

 bly a subordinate land lobe at McAlester in Oklahoma. 



la. Mississippi land lobe, extending through northern Missis- 

 sippi and northwestern Alabama. 



2. Birmingha^n sea lobe, a small lobe in central Alabama. 

 2a. Rome land lobe with a moderate curve. 



3. Knoxville sea lobe, with its apex looping around the Knox- 

 ville area. 



3a. Alleghany land lobe — along the main line of the Alleghany 

 Mountains of Virginia. 



4. P cnnsylvania sea lobe, a marked lobe with the apex in cen- 

 tral Pennsylvania, the trend changing to nearly east. 



4a. Nezu York land lobe, the apex being near New York City. 



5. Champlain sea lobe, east of the Adirondacks. 



