172 GUIDEBOOK OF THE WESTERN UNITED STATES 
one of these cones are well exposed by a quarry and cut a few miles 
Chislealia beyond Chiricahua siding. Between two cones 5 
Elevation 4,671 feet, ules southeast of Chiricahua siding is a very remark- 
New Orleans 13H able crater closely similar in character to the Kilbourne 
ae Hole and Hunts Hole, southwest of Lanark. (See p. 
134.) Itsrim is dimly visible from the railroad. It is a huge oblong 
hole a mile long and about 200 feet deep. The bottom, now a smooth 
surface of alluvium, is encircled by a wall of lava of the flow that con- 
stitutes the surface of the surrounding country and was probably 
derived from craters marked by cones to the north and south. Upon 
this wall is an encircling rim, in places 150 feet high, of fragmentary 
material, lava, cross-bedded sand, or soft sandstone and many frag- 
ments of limestone containing Comanche fossils from strata that un- 
derlie the valley and crop out init not many miles southeast of the cra- 
ter. (See fig.44.) This 
feature is believed to 
have been caused by 
a volcanic explosion 
after the lava flow. 
This region is called 
the San Bernardino Valley from an early settlement at the San Ber- 
nardino ranch (now the Slaughter ranch), on a Spanish land grant 
that straddled the present international boundary. The ranch house 
is about 10 miles southeast of the railroad. A main road to the west, 
laid out by Lieutenant Colonel Cooke and the Mormon Battalion, 
a division of General Kearny’ s Army of the West, went through this 
RPS oe “ese 
AANA 
_ Figure 44.—Section across explosion crater 5 aes southeast of 
Chiricahua siding, Cochise County 
place i in 1846 and, passing near 
Douglas, followed down the San 
‘Many of the details of flow are clearly 
shown by the surfaces, w 
places are ropy, as the lava puckered 
d in others are glassy 
in congealing, an 
basis smooth like slag from a blast 
sas gtk OF crplntoas ot Rake 
The | in of the flow presents an 
: i. pushed along by the advance of the 
_ flow. In places a cinder cone was 
lt COD a Sacliphegomange 
hich in some | 
an orifice. In its last stages the action 
was mainly a violent escape of steam, 
which blew out a large amo of cin- 
dery or pumiceous material, together 
with a few hardened masses of lava. 
This was all thrown to a considerable 
height in the air and then fell on all 
sides, quickly b 
recent date of these eruptions is indi- 
cated by the fact that the piles of loose 
material have not been affected by the 
powerful erosional processes of the re- 
gion, and there i is no perceptible oxida- 
the roofs of the tunnels. Also, the lava 
and cinders lie on sand deposits that 
are of Recent age, 
