OCCURRENCE OF COAL WITH UNUSUAL CONDITIONS 323 
more, the deposition of each one of the nine was either begun later 
than that of its neighbor to the southwest, and was completed later, 
Fic. 3.—Generalized sketch of five of the crests and a portion of another, showing 
the relation of the coal deposits to the inclined bedding of the sandstones. Solid 
black lines, coal; dotted lines, bedding planes, usually with a black stain. 
Fic. 4.—An occurrence of coal on one of the crests. In this case the sands were 
derived from both directions. Drawn correctly to scale from photographs and 
sketches. 
Fic. 5.—Ideal representation of the occurrence shown in Fig. 4, before com- 
pression. 
or was begun entirely after this neighbor had been formed. Each 
pocket was formed at the toe of the advancing sand deposit, to be 
later covered and checked in its growth while a new deposit of 
