DENVER OF GREEN MOUNTAIN. 173 



measured, but as the latter lias a dip of 45 and as it is shown by adjacent 

 outcrops that the fold is here sharp and that the transition from vertical 

 beds to those having a dip of 45 is sudden, it seems highly probable that 

 some of the lower l>eds of the Denver series are vertical on the section 

 line. From the dark conglomerate the exposure is almost continuous, and 

 although sharp bedding planes are so rare as to make accurate dip meas- 

 urement difficult, still the gradual changes an- visible and they agree 

 closely with the drawn section. Dip measurements were made as follows: 

 42 between d and c; 18 c in//.- lo in A. 



For convenience in discussing the section, four divisions are mad< — A, 

 ]'», C, and D. 



Division a, 5 8o feet. — This emliraces all up to the dark conglomerate. No 

 outcrops of importance occur on or near the profile line of division. 

 Its base, which is also the base of the formation, is an assumed point 

 deduced from the known thickness of the Arapahoe beds in the vicinity, 

 their known strike, and vertical position. A few yards south of the line 

 of profile is a smooth ridge showing here and there crumbling, sandy strata 

 of the Denver formation, and also farther west the upper Arapahoe clays. 

 The outcrops here are not numerous enough to permit a determination of 

 the line between the formations with accuracy. 



This division must include strata corresponding to those described in 

 Table Mountain, but the detailed constitution can hardly he the same here, 

 or else more distinct outcrops would have resulted. The strata occurring 

 about 100 feet below the basalt forming an alternating series of tuff 1 , 

 gravel, and clay layers of light color, are apparently not represented 

 here, as such material would surely have been discoverable in the ridge 

 mentioned near the profile line, or in some others on the western slope of 

 the mountain. The i'vw exposures in Section Ravine to the southward, 

 which have already been mentioned (p. 160), show thai the lower horizons 

 are composed of very loose and friable clays and sand rocks, and the 

 absence of firm outcrops on the section line is not at all remarkable. 



Division b, 50 feet. — This division embraces the dark conglomerate and the 

 gravelly transition beds immediately above and below it. Without being 

 able to trace the actual connection on the surface this conglomerate is 



