A generalized section for the western part of the Denver Basin is introduced here for the use of local students. The formations normally present in this region are shown in their usual position. They are briefly described on the chart, and their thickness is indicated by figures which may be regarded as near the maximum for the district. The section will apply to most of the foothills area between Morrison and Boulder though surface features and thickness of beds will vary considerably from place to place. Certain of the formations are known to be fossil bearing, others barren or nearly so. When fossils are present they are usually restricted to certain localities, and these may be widely scattered. The following remarks apply to the possibilities for finding fossils in the formations named. _Denver and Arapahoe._ Leaf impressions of palms, ferns, and numerous species of well-known trees and shrubs are common in many localities. Petrified wood is fairly abundant, and a few scattered bones of reptiles and mammals have been found. The two formations are treated as a unit because the Arapahoe is neither conspicuous nor sharply defined. Denver beds are well exposed on the slopes of Table Mountain at Golden; fossils, however, have been obtained from several localities nearer the city of Denver, notably from the hills just west of Overland Park. _Laramie._ Plant material is locally abundant, principally the leaves of familiar deciduous trees, palms, and ferns. Many of the clay pits being worked near Golden are in this formation. Oysters and a few other mollusks may be found in some places. _Fox Hills._ Better exposures of this formation are located to the north of Denver. Marine mollusks are most frequently found. _Pierre._ In addition to the characteristic dark shales, this formation includes some limy material and sandstone beds, both of which are fossiliferous in places. Two types of marine mollusks are characteristic: _Inoceramus_, generic name for several species of clam-like bivalves readily identified by concentric elevations which produce a rippled effect on the shell surfaces; and _Baculites_, cephalopods with straight, chambered shells which often break at the suture lines, where the fossil is weakened by the chamber walls. Small oyster shells are fairly common also. The formation is to be found some distance to the east of the prominent hogback where it weathers into smooth surfaces in the form of broad valleys and flats, with rounded contours on the few elevations that may be present. It forms a soft, flaky soil when dry, is a sticky “gumbo” when wet. The clay is generally of a rather dark grayish color when freshly exposed but it takes on a rusty appearance after weathering. At various levels there are numerous iron-cemented concretions, many of which contain fossil shells.