654 THE JOURNAL OF GEOLOGY. 
basin character is a prominent feature. J¢ 2s found in working 
the second seam that the thicker low-lying coal overlies the areas from 
which the swamp coal was taken in the third seam. 
The opportunities for thus testing the truth of this theory 
are, in this field, quite rare since only a very small number of 
the mines ever work more than one seam. 
H. Foster Barn. 
IowA GEOLOGICAL SURVEY, 
May 25, 1895. 
