614 INDEX TO THE STEATIGRAPHY OF NORTH AMERICA. 



lower fauna characteristic of the Magothy and Matawan and the Black Creek has been found 

 in the lower part of the Ripley formation and in the Selma chalk, also in the Eutaw; the 

 upper fauna of the Monmouth and the Peedee is found in the upper part of the Ripley and 

 the Selma. The flora of the Magothy characteristic of the New England area and of New 

 Jersey and Maryland is represented in the Black Creek and also in the Tuscaloosa of western 

 Alabama and Mississippi. 



The Cretaceous formations of the northern Atlantic Coastal Plain have been correlated with 

 the recognized European subdivisions and the faunas and floras examined have led Clark and Berry 

 to propose the approximate equivalents given in the table on page 612. The Lower Cretaceous 

 floras are regarded as comprising the Neocomian to the Albian, the Patuxent flora being dis- 

 tinctly a Neocomian flora and the Patapsco an Albian flora. The Upper Cretaceous floras and 

 faunas extend from the Cenomanian to the Danian, the Raritan flora containing a large Ceno- 

 manian element, while the Magothy and Black Creek floras are regarded as Turonian. The 

 faunas which are found in succeeding beds are in the Matawan and Black Creek apparently 

 Turonian, although regarded by some paleontologists as Senonian; those of the younger Mon- 

 mouth and Peedee are unquestionably Senonian. The later Rancocas and Manasquan faunas 

 of the northern part of the Coastal Plain are regarded as Danian and probably belong to the 

 horizon of the Maestricht. 



J 14. CENTRAI, KANSAS. 



Cragin "^ describes the occurrences of marine Lower Cretaceous in Saline 

 County, Kans., in part as follows: 



The Mentor beds, named from a small station in Saline County, Kans., within the area of 

 their outcrop, are a terrane of variegated, earthy-textured marine shales, with intercalated 

 beds of brown sandstone, resting in part conformably upon the Kiowa shales and in part uncon- 

 formably upon the drab and purple-red laminated shales and impure limestones of the Per- 

 mian, and succeeded above by the more heavily arenaceous fresh-water sediments of the Dakota. 

 They were formerly considered by all geologists as constituting a part of the Dakota group, 

 but are now known to belong to the upper part of the Comanche series. * * * 



The shales of the Mentor beds are chiefly argillaceous, but they contain a greater or less 

 admixture of sand, to which, as soft sandstones, they locally give place in certain horizons. 

 They apparently contain some hme also, partly in the condition of sulphate. * * * Such 

 outcrops of the shales as do occur present themselves either as limited, more or less steep-faced 

 banks of marly-appearing clay, of white, ferruginous-yellow, red, or blue color, or particolored 

 with two or more of these. Their coloring seems to be the result of the variable distribution 

 of oxide, peroxide, and sulphates of iron. 



The sandstone of the Mentor beds occurs in thin, local strata. While these are of shght 

 consequence judged by the space they occupy, they are nevertheless of great stratigraphic 

 importance, since it is from these alone that our knowledge of the geological age of the Mentor 

 terrane has been derived. * * * 



The thickness of the Mentor beds varies greatly, since that portion of the terrane that 

 rests directly upon the Permian lies unconformably upon the latter and presents considerable 

 differences in the elevation of its base. It probably nowhere greatly exceeds 60 or 60 feet. 



The Mentor beds are thus seen to be characterized by a fauna related to that of the Denison 

 beds and still more closely to that of the Kiowa shales. Their fauna is, in fact, especiaUy related 

 to that of the upper part of the latter. 



The stratigraphic relation to the Kiowa shales is also close. While the Mentor beds gen- 

 erally rest upon the Permian in Saline County, they rest in part upon the Kiowa shales farther 

 southward, as shown by the occurrence beneath them of black shales amongst some of whose 

 fossils, submitted to the writer from a few miles west of Lindsborg by Prof. J. A. Udden, are 

 Modiola stonewallensis nob. and Splienodiscus pedernalis Roem.; but whether they are to be 



