56 SUEYEY OF COLORADO AND NEW MEXICO. 



have no doubt tliat there are beds of coal. The mesa, of which Eaton 

 and Fischer's Peats form parts, is undoubtedly the overflow of a dike, 

 which seemed to take a general direction northeast and southwest, and 

 toward the northeast appears to incline about ten degrees. 



In ascending the Eaton Mountains by the road the cretaceous beds 

 soon disappear; the tertiary come in mth coal and soon disappear in 

 turn. The dip of these beds I found difficult to determine, and, I think, 

 when there is any, it is local, and that in the aggreg'ate they may be re- 

 garded as nearly horizontal. Just before reaching the toll-gate, near Mr. 

 Wooten's, the sandstone inclines northward about fifteen degrees. 'Near 

 the toll-gate, by the side of the road, a bed of impure coal, two feet thick, 

 has been ex^josed. In a ravine farther south there is an opening from 

 which coal is taken for fuel, the bed being fom- feet thick and of excellent 

 quality. This bed has some impure coal above and below, and when 

 oi)ened 1 think that it will i)rove to be from six to eight feet thick, good 

 coal. The grass and debris so cover these hills that it is impossible to 

 get a connected section of the beds, but the usual claj'S and sandstones 

 occur above the coal. 



Toward the southern end of the pass there are some perpendicular walls 

 of sandstone which show a vertical cleavage, strike southeast and north- 

 west. In this sandstone are two or three small seams of coal, two to four 

 inches thick, which break the lines of cleavage and interrupt them. This 

 sandstone is from one hundred to one hundred and fifty feet thick, and 

 immediately beneath it is an irregular bed of the alternate thin layers 

 of the mud sandstone and clay, which I have called a bed of passage 

 between the cretaceous and tertiary of this region. I call it a sort of 

 mud shale, as the sediments seem to indicate a continuous mud flat, 

 with the surface of the sandstones and shales covered with all sorts of 

 mud markings. As we emerge from the Eaton Mountains southward to 

 the plains we find a large thickness of this mud shale with the sandstones 

 above. There seems to be three hundred to four hundred feet of sand- 

 stone, with a cap of basalt. At the foot of the hills there is a dike Arith 

 a strike northeast and southwest, with a width of about six feet. This 

 dike is shown on the west side of the road in the form of a pile of hori- 

 zontal columns, like cordwood, fifty feet high or more. Some of the 

 columns are five-sided, but mostly four-sided. 



All along our right hand the high hills are iDreciselyas they were from 

 Spanish Peaks to Trinidad. These bluff-hills continue like an irregular 

 wall as far as Maxwell's. They are cut up by side streams into cones and 

 ridges, giving a wonderful i^icturesqueness to the scenery. This range 

 of hills presents the same kind of shore-line as is seen north of the 

 Eaton Hills, with the lower cretaceous shales and the sandstone in juxta- 

 position. On the east side of the road, broken portions of these ridges 

 extend down southward or southeast. Scattered over this broad plain 

 are buttes and mesas — isolated exhibitions of the basaltic rocks. The 

 tertiary beds soon cease in the plains to the eastward, and the cretaceous 

 beds occupy the country. That all this beautiful valley or plain on the 

 east side of the Eaton Hills has been carved out of the tertiary strata 

 appears to me most probable. Why the eroding agency left such a belt 

 of hills as the Eaton it is difficult for me to determine, but I am dis- 

 posed to believe thatit acted from the northwest toward the southeast, 

 and was local. The direction of all the benches of cretaceous material 

 left in the valley, as well as that of the mesa tops, has this general trend, 

 and the map will show the numerous branches which flow from the moun- 

 tains into the Canadian Eiver through these tertiary hills. I have called 

 the bluff-hills on the west side of the road a shore line, because they pre- 



