52 GUIDEBOOK OF THE WESTERN UNITED STATES. 
In this region the strata rise southwestward at a rate slightly 
greater than that of the railway grade. This structure is shown on 
the cross section on sheet 9, which represents not only the attitude of 
the rocks but also the relative thickness of the formations and facts 
revealed by deep borings at intervals. 
The old Santa Fe Trail passed 400 feet east of the site of the sta- 
tion at Timpas. A short distance beyond this place the Timpas 
limestone caps mesas ' or buttes of considerable promi- 
bale svar nence, especially along the east side of the track, and 
Psa riapat feet, & little farther southwest it extends southward in 
a long line of low westward-facing cliffs. Below these 
cliffs are slopes of Carlile shale, at the foot of which, near Ayer, is 
a bench of the Greenhorn limestone. Along this poston of the 
valley of Timpas Creek, on both sides, are excellent exposures of 
long, sloping mesas capped by the Timpas limestone. This rock, 
though soft as rocks 
go, is much harder 
than the shales and 
d@ remains where the 
overlying shale is 
Figure 6.—Section across Timpas Creek roe near Bloom, Colo., 
looking southwest. a, Timpas limestone; b, Carlile shale; ¢, washed away. . The 
Greenhorn iain 2 Graneros shale, limestone ec aps pro- 
ject in a cliff presenting the greater part of the thickness of the 
formation. Most of the mesas slope to the northeast because the 
limestone dips in that direction. 
From Symons to and beyond Bloom the ordinary features presented 
in the Timpas Creek valley are a low, wide bench or shelf of Greenhorn 
limestone at or near the bottom and a slope of about 
200 feet of Carlile shale, rising to a cliff at the edge of 
,. the tabular surface of the mesa of Timpas limestone. 
” (See Pl. V, A, p. 29, and fig. 6.) 
The areas of Timpas and Greenhorn limestones carry a small growth 
of “cedars” (Juniperus occidentalis), termed sabina by the people of 
the country. The cane cactus (Opuntia arborescens) becomes con- 
spicuous in this vicinity and is abundant to the south and west through 
Colorado and New Mexico, together with flat-leaved cactuses of 
various species. (See footnote on pp. 155-156.) 
The Dakota sandstone is exposed a short distance west of the rail- 
way at milepost 590, being brought up by a low dome, as shown in the 
cross section on sheet 9. The outcrop of this sandstone extends to 
Delhi and beyond, with the adjoining higher slopes of shales and 
limestone in a relation closely similar to those shown‘in figure 7. 
Bloom. 
a 4,773 sane 
601 m: 
1 Mesa (may’sa), a Spanish word mean- | lar surface is called a cuesta (kways’ ta), 
ing table, is applied to a flat-topped butte | from one of the Spanish words for hill. 
a hill, ve one that has a sloping tabu- 
