54 GUIDEBOOK OF THE WESTERN UNITED STATES. 
Indian name has not been retained, especially as there are other 
Spanish Peaks in the West. A remarkable feature of this intrusion is 
the large number of narrow dikes of the igneous rocks, mostly branch- 
ing from the large masses through cracks in the sedimentary strata 
and extending out in every direction for many miles from the foot 
of the peaks. Owing to their hardness they stand above the surface 
as narrow walls in many places. One of these is shown in Plate 
VU, B. The sandstones and shales adjoining the larger igneous 
masses are baked and otherwise altered by the heat of the intrusion 
and are considerably upturned. 
Half a mile north of Tyrone a granite marker just east of the track 
indicates the location of the old Santa Fe Trail. Behind the Spanish 
Peaks rise the main Rocky Mountains, here called 
Sangre de Cristo Range (sahn’gray day cris’to, Span- 
ish for blood of Christ). Fishers Peak, east of Trini- 
dad, is also visible from the plateau about Tyrone, but 
is almost straight ahead of the line of railway. Five miles beyond 
Tyrone. 
Wi +i, & FON fant 
Kansas City 624 miles. 
West Peak East Peak 
Figur 8.—Section through Spanish Peaks, west of Tyrone, Colo., looking north. Underground relations 
largely hypothetical. ; 
Tyrone the train enters a wide area of shale. (Apishapa) lying nearly 
level and extending to Hoehne siding. The shale includes limy 
layers, some of them of light color and many of them weathering to 
a light-yellow tint. One of the best exposures is in a ditch north of 
the track, near milepost 620, where the unweathered shale is black. 
The water of this ditch is brought from Purgatoire River, some dis- 
tance to the southwest, and serves to irrigate a small area about the 
new village of Poso, which is at milepost 615. 
Beyond Earl the route crosses a low ridge of Apishapa shale and 
thence southwestward descends into the valley of Purgatoire River, 
the west side of which is followed to Trinidad. 1 
oy stream, which wes passed farther east at Las Animas, 
Elevation 5,673 feet. > 5 ; * 
saber pon tot a brings considerable water from the mountains west of 
Trinidad and is especially subject to freshets, some 
of which cause great damage along the lower part of the valley. 
The greatest known flood, in 1904, had a volume of 45,000 second- 
feet. In 1912 nearly 36,000 acres of land was irrigated by water 
from this stream, most of it in the region between Trinidad and Las 
Animas, 
