132 STANTON & KNOWLTON — LARAMIE AND RELATED FORMATIONS. 



Associated with these there were a number of small bones, teeth, 

 etcetera. This is noteworthy as the lowest horizon at which fresh-water 

 invertebrates were found in this region. 



The area underlain by the nearly horizontal Ceratops beds is an un- 

 dulating grass-covered country, in which Lance creek, Lightning creek, 

 and their tributaries have cut valleys 200 to 300 feet below the general 

 level. Along their banks there are frequently nearly vertical cliffs 40 to 

 100 feet high, and the side gulches often exhibit typical bad lands erosion, 

 so that there are numerous good exposures. The bedding is very irregu- 

 lar, however, sandstones passing horizontally into shales and vice versa, 

 and it is difficult to fix exactly the relative positions of beds in different 

 exposures. The very limited horizontal extent of some of the sandstones 

 seems to have determined the topographic forms of the rounded hills 

 capped by hard sandstone that are common on both sides of Lance creek. 



Another peculiarity of the sandstones seen on Lance creek near the 

 old U-L ranch and on the divide between Lance and Lightning creeks 

 consists of very large indurated masses of sandstone, which, for want of 

 a better name, we have called concretions, as Mr Hatcher also has done. 

 Some of them are spherical, but the more common forms are elongated 

 like irregular cylinders, often many feet in length, tying horizontally in 

 the bed. More frequently the surface is smooth, but some specimens 

 were seen quite regularly fluted. They are left scattered over the ground 

 by the erosion of the softer enclosing sandstone and form very striking 

 objects. They are probably not confined to a single bed, but the vertical 

 range of the horizons in which we observed them is probably not more 

 than 200 feet. They occur about 1,500 feet above the base of the Cera- 

 tops beds, not far from the horizon of the fossils last mentioned, and, 

 according to Mr Hatcher, some of the specimens of Triceratops have been 

 found in the concretions themselves. Professor J. E. Todd has observed 

 and described* similar elongated masses in the Laramie near the head 

 of Grand and Moreau rivers, South Dakota, some 200 miles north of the 

 Lance Creek localities. He found there concretions arranged in longi- 

 tudinal systems, and suggests that they mark the position of ancient 

 beaches. Unfortunately we had not received Professor Todd's paper 

 before going into the field, and the arrangement was not particularly 

 noted, though it is our impression that no such regularity obtains where 

 our observations were made. 



Our largest collections of plants and invertebrates also came from this 

 portion of the series. One of the best localities is in a bluff on the right 

 bank of Lance creek just below the U-L ranch, where the following in- 

 vertebrates were obtained : 



* L,og-like concretions and fossil shores. Am. Geologist, vol. xvii, pp. 347-349, June, 1896. 



