A broad asymmetrical anticline forms the southern Laramie Mts., with the Precambrian exposed in the core. It is bounded by the Denver-Julesburg and Laramie basins. Rocks in the area surveyed are syenites, norites, hornblende gneiss, Sherman Granite, anorthosite, and sedimentary rocks in the basins. Four profiles are given. Good correlations exist between the gravity field and geology. Anomalies within the core are greater than those between the Precambrian and adjoining basins. Relatively low values, -145 to -165 mgal are found over anorthosite, and high values of -175 mgal over Sherman Granite. A hypothetical model indicates that this density contrast extends to a depth of about 7 km.