32 LARAMIE BASIN, WYOMING. 
These sections show the variability of the formation within short 
distances. 
At the north end of the Cloverly hogback on the east side of the 
Centennial Valley, in sec. 18, on Little Laramie River, there is a sec- 
tion in which the formation is seen to consist of 10 feet of massive 
sandstone, 100 feet of flaggy ferruginous sandstone and shale, and 
(at the base) 40 feet of massive white sandstone. The basal sand- 
stone is conglomeratic in places. Below this sandstone are 30 feet 
of ferruginous shales which may belong either in the Cloverly or 
Morrison formation, and then 300 feet of typical bluish to purple 
Morrison shales. On the south bank of Laramie River north of Jelm 
Mountain the Cloverly formation has at the top 25 feet or more of 
buff flaggy sandstone; then 60 feet of shales, greenish above, buff 
below, with some layers of flaggy white sandstone; and at the base 
23 feet of flaggy buff sandstone. The relation of the basal sandstone 
to the Morrison formation is concealed by talus. In the hill 2 miles 
south-southwest of Howell station the formation is only about 50 feet 
thick, consisting of two massive, coarse, hard sandstones separated 
by dark shale which has been prospected for coal. In the ridge 
north and northwest of Medicine Bow the Cloverly formation is 140 
feet thick. In the prominent butte on the axis of the anticline north 
of Bone Creek it is 150 feet thick and consists of three sandstones 
separated by gray and purplish shales and clays. Northwest of 
Bootheel Butte the formation appears to consist entirely of hard gray 
sandstone and the thickness is less than in the region farther south. 
BENTON FORMATION. 
Distribution and general relations. — A large portion of the Laramie 
Basin is occupied by the dark shale of the Benton formation. It 
outcrops at intervals from the foot of Jelm Mountain northeastward 
past Laramie, through Wyoming station and south of McGill to old 
Rock Creek station, but owing to the softness of its materials it has 
been deeply eroded, and it is largely covered by Quaternary deposits. 
It is extensively exhibited from the Wheatland reservoir westward 
through Rock Creek and Como Ridge, in the anticlinal ridges north 
of Medicine Bow, along the east side of Medicine Bow Valley and all 
around the Freezeout Hills, in the vicinity of the Hutton Lakes, in 
the hills 1| miles southwest of Howell station, and in the railroad cuts 
extending from a point a mile north ot Howell to Wyoming. It dis- 
appears beneath Tertiary deposits southwest of Little Medicine Bow 
post-office. Its outcrop extends along both sides of the Centennial 
Valley and it appears in small areas on Laramie River above Woods 
Landing and in the slopes west of Red Mountain. 
The formation appears to lie conformably upon the Cloverly for- 
mation and to be succeeded conformably by the overlying Niobrara 
formation. In the southern part of the basin the thickness is nearly 
