forms steep, much dissected, bluffs, which give to the reservoir its name. The dip changes rapidly at the latter place. Along the ridge from Terry Lake northward the dip is easterly and only about 5˚. Then it changes to N and then N by NW (remains about 4˚ or 5˚) and swings around to the north end of Rocky Ridge Reservoir No. 1 , the strike changing in response to change of dip. There is a series of reservoirs about which large flocks of ducks and numerous large gulls were flying. The sandstone, as at Fossil Ridge, contains large numbers of Inoceramus oblongus and some of the other Inoceramus found at Fossil Ridge, but I only saw two or three Pinna lakesii and Baculites compressus , one Callista , one Scaphites nodosus , and a very few Ostrea cf. O. inornata . Anomia raetiformis is common