THE DAKOTA SANDSTONE. 
—_—— 
THE MENTOR BEDS. 
DESCRIPTION. 
In eastern-central Kansas, in the lower part of what has generally 
been called the Dakota sandstone, are occasional outcrops of very 
dark brown fossiliferous sandstone so friable, as a rule, that it does 
not form a ledge, but its presence is shown by loose blocks on the 
slopes of the hills. For this terrane, Professor Cragin has proposed 
the name, Mentor beds, the typical exposure being on the eastern 
side of the Smoky Hill river about three miles east of the Union 
Pacific R. R. station of Mentor. 
Mentor is in the Smoky Hill valley on the western side of the 
river seven miles south of Salina and is apparently underlain by the 
Wellington shales. Professor Cragin has described the lithologic 
characters and stratigraphic position of these beds and says they 
are composed “of variegated, earthy-textured marine shales, with 
intercalated beds of brown sandstone, resting in part conformably 
upon the Kiowa shales and in part unconformably 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. * * * The shales of the Mentor 
beds are chiefly argillaceous, but they contain a greater or less ad- 
mixture of sand, to which, as soft sandstones, they locally give place 
in certain horizons. * * * Being little consolidated, they 
weather into gentle slopes and broad, low, rounded eminences 
scarcely worthy the name of hills, and present few conspicuous out- 
crops. 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 parti-colored 
with two or more of these. * * * 
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