256 EXPLOEATIONS ACEOSS THE GEEAT BASIN OF UTAH. 



Between Cottonwood and Rock Creeks small outcrops of argillaceous and arena- 

 ceous shales were observed, and only nearer to Rock Creek, 20 feet of light-brown 

 and purely quartzose sandstone. On Rock Creek the followiug section was obtained : 

 On top of the hill, about 150 feet above the creek, there is a layer of dark-brown, 

 very hard ferruginous sandstone, partly even-grained and partly of a coarse, uneven 

 grain. Inside most of the pieces are much lighter colored and less cemented, even 

 friable. Then follow — 



80 feet of slope, with occasional outcrops of shale and sandstone, some of which 

 is very compact and finely grained. 



40 feet of white, purely quartzose sandstone, with an even and rather fine 

 grain, and easily crumbling. It generally does not show any distinct stratification. 

 The lowest 30 feet are gray and white argillaceous shales, not all well exposed. 

 There, also, I did not find any organic remains, except indistinct impressions of 

 wood, in the ferruginous sandstone, on top of the hill. I have, however, little doubt 

 that, if not the whole section, then, at least, this upper bed, is Lower Cretaceous, the 

 No. I of the Nebraska section; and the whole may correspond to the Arenaceous 

 group and Marly Clay group of Dr. Shumard. West of Rock Creek the exposures 

 are scarce, the rocks being too friable, and easily disintegrate ig. Only on the hills, 

 toward Little Sandy Creek, I noticed strata similar to those on Rock Creek — white 

 quartzose sandstone, overlaid by gray and white argillaceous shales, with arenaceous 

 and ferruginous portions and seams — and higher up large flags of dark-brown ferrugin- 

 ous sandstone. A little farther on, the hills which overlook Little Sandy Creek are 

 capped by white limestone, nearly made up of hwceramus {Inoceramas pscudomytih'uhs 

 and I. avwutoides), and in which also a Bamhtes was found. They correspond to No. 

 Ill of the Nebraska Cretaceous section of Messrs. Meek and Hay den, which is so largely 

 developed on the Upper Missouri. Underneath this rock follows a series of argilla- 

 ceous shales about 40 feet thick, which seems to be an equivalent of No. II of the Ne- 

 braska section; and on the creek the ferruginous sandstone is exposed, apparently the 

 No. I of that section* 



The last small outcrops of the Cretaceous limestones and marls were observed on 

 Big Sandy Creek, and near there, on Little Blue River, but they evidently continue 

 near the surface a considerable distance farther up that river, as we may judge from 

 the growth of timber in the creek bottom. While with Lieutenant Bryan, I found these 

 limestones and marls consider;) lily farther west, ne ir the una '-\ •■ ighth degree of longi- 

 tude, only a few miles south of Little Blue River, and on the Republican, from 74 

 miles above Fort Riley, near longitude 97° 25', and latitude 39° 38' — where I observed 

 a section quite similar to that on the Little Sandy — extending about 100 miles, to long 

 itude 98° 45' and latitude 40° 05'. On Solomon's Fork they are found still farther 

 westward. 



* Although I have no paleontological evidence that thi - nl ; >■ i i- N" .. 1, stn! I - hi ul — tin no doubt in that 

 respect. It underlies the other. Cretaceous strata, and me as the rock which 1 have found largely 



developed on the Republican River, where, about 75 miles above Fort Riley, it holds the same relation to the Inoceramus 

 beds, the same which Mr. Meek, Dr. Hayden, Dr. Newberry, Mr. Hawn, Mr. Pratten, and others have frequently seen in 

 the same position, as well in Kansas as in Nebraska, and in which, at many of these localities, nam 

 dycotyledonous leaves have been discovered. 



