RECONNAISSANCE IN COLORADO AND UTAH 647 
ous with persistent characters from northeastern Utah to the great 
esplanade bordered by the White Cliffs in southern Utah facing the 
Grand Canyon. ‘The characters of the White Cliff repeatedly empha- 
sized are its massiveness, “oblique lamination” or “‘false stratifica- 
tion,’ and its white, golden, orange, or light-red colors, which are 
so brilliant in the desert air. 
The upper boundary of the White Cliff is the basal marine lime- 
stone of the Flaming Gorge Group, of Powell (33). The lower 
Fic. 2.—Looking-glass Rock. Near southwest base of La Sal Mountains, Utah, 
to east of road from Monticello to Moab. Formed of alcove-making upper sandstone 
of La Plata formation. At rear of recess is an opening through to other side of rock. 
The scale is indicated by figures of two men outlined against sky through opening. 
boundary is less clearly defined in the statements of Powell and 
others, but, with recognition of the stratigraphic break soon to be 
mentioned and the marked color line apparently everywhere present 
at the summit of the Triassic sandstones, it may be hoped that no 
great difficulties in drawing the base of the White Cliff will be experi- 
enced when the attempt is seriously made. 
UNCONFORMITY BELOW THE LA PLATA SANDSTONE 
The far-reaching unconformity below the fresh-water Jurassic 
beds of central Colorado, by which they overlap all older Mesozoic 
