1890] MARYLAND ACADEMY OF SCIENCES. 97 



NOTES AND ILLUSTRATIONS TO "OBSERVATIONS ON THE 



CRETACEOUS AND EOCENE FORMATIONS OF 



MARYLAND." 



By p. R. UHLER. 



Continued studies of sections exposed in various parts of the 

 sedimentary region, described in the two former papers printed 

 in these Transactions, have brought out more distinctly many 

 of the relations and combinations of several characteristic 

 divisions of both the Cretaceous and Eocene deposits on the 

 Western Shore of Maryland. 



It is now possible for us to recognize here, without much 

 difficulty, most of the principal members of the Cretaceous 

 system as they occur in the State of New Jersey. In order to 

 give a distinct idea of these beds and strata, as far as we have 

 found them to exist here in a single series, we have added a 

 diagrammatic sketch on a horizontal scale of one mile to an 

 inch, along a register line, extending from the head of Marley 

 Creek to the Severn and continuing along the north shore of 

 that river to near its mouth. 



It will be observed from an inspection of Plate A that the 

 Potomac Formation lies at the base of the series, farthest 

 inland, and is consequently the oldest of the column. A few 

 miles further northwest it rests upon the primitive rocks, and 

 is thus seen to be the lowest of our sedimentary formations. 



It is composed of beds of sand, fuller's earth, gravel and 

 cobble-stones at base, while farther up it consists of beds and 

 thick strata of indurated clay, sandy clay and broken clay, 

 interstratified with quartz sands of angular grains. The coarse 

 sands of the lower division are often charged with nests and bits 

 of fuller's earth or kaolin clay. A thin belt of dense iron paint- 

 stone usually rests on top of the coarse white sand of the basal 

 series, and separates it from the stratified grits and lead-colored 

 fossiliferous clays of the series next above. Above this rests a 

 series of pale and red clays, often broken and mixed near or at 

 the surface, usually called " variegated clays," more or less 

 invaded by sands, and sometimes carrying sparsely distributed 

 quartz pebbles. 



Into the eroded figure of this Potomac formation the Colum- 



[JDNE7, 1890.] 



