98 The American Geologist. February, 1902. 
Lthe so-called “Trias’—the Red Beds. No line of demarka- 
tion was found between this formation and the Trias. 
Mr. Cross in his study of the Pikes Peak region* describes 
a similar series which’ he calls the Fountain formation, the 
thickness of which he estimates at 1,000 feet. According to 
his description, the Fountain is very similar to the Perry Park 
beds. He says,—‘They are chiefly coarse-grained, crumbling, 
arkose sandstones in heavy banks showing cross bedding. 
They are locally conglomeratic, mottled with gray and various 
light shades of red. * * * Near the base and at intervals 
throughout the series, are very dark red or purplish layers of 
arenaceous clay or fine-grained sandstone.” This reads as if it 
were written for the Perry Park beds. The Pikes Peak quadran- 
gle corners upon the Castle Rock quadrangle. It is, therefore, 
near enough to give weight to correlation on stratigraphic and 
lithologic grounds. It is probable, therefore, that some part 
at least of the sandstone series above the fossiliferous lime- 
stone of Perry Park is an equivalent of the Fountain forma- 
tion. Mr. Cross shows that the Fountain probably belongs to 
the Carboniferous. If this be true it is possible that some part 
of the Red Beds along the mountain front which have been 
called Trias may belong to an earlier age. If the fossil bearing 
stratum marks the middle of the lower Carboniferous as Mr. 
Girty thinks; and if the overlying sandstones and conglomer- 
ates are also Carboniferous; and if these together with the 
Red Beds proper—the so-called Trias—make a conformable 
group, as seems to be the case, it would seem rational in the 
absence of evidence to the contrary, to refer at least the lower 
part of the Red Beds to the Carboniferous, as Hayden sug- 
gested in his report of 1874 (p. 42). It seems rational, furth- 
ermore, to suppose that the Permian may also be represented 
in the Red Beds. This supposition is borne out to some ex- 
tent by the facts published in another article in which I have 
shown that the Red Beds of the mountain front extend east- 
ward and southward without obvious change in character to 
the Canadian river, New Mexico, where they are referred to 
the Permian by R. T. Hill. 
4—11,—The Red Beds, Morrison, Dakota, Benton, Nio- 
brara, Fort Pierre, Fox Hills, and Laramie are all represented 
*U. S$. Geol. Surv. Pikes Peak Folio. 
