134 GUIDEBOOK OF THE WESTERN UNITED STATES 
Eight miles southwest of Rutter siding are two large “holes” in 
the wide terrace plain which have been a source of much wonderment 
for many years. They were originally called Los Corrales de Piedra 
(rock corrals). The more northerly, Kilbourne Hole, shown in 
Plate 18, B, is 300 feet deep and is encircled by a rim of loose mate- 
rial 50 to 150 feet high, so that at many places it has a total depth 
of 450 feet, with a maximum of 463 feet. 
sw. 
The diameter is nearly 
ee ae Se oe 
SS een Samar soe ee a 
PyWAx aad) 
Fi 
wy 
BWranrer 97 <Q, ti th 
PIGURE 4i- 
t fre t q y 2 miles west of El] Paso, Tex. Is, Limestone, and 
ss, sandstone, of Upper Cretaceous age; Kdr, Del Rio horizon; sh, dark shale; Kf, Fredericksburg 
group; Tp, intrusive porphyry 
2 miles. Hunts Hole, 2 miles south, is closely similar but smaller 
and has a rim of less height. A third one, Phillips Hole, to the 
southeast, is only about 50 feet deep and has no rim. The mate- 
rial in the wall of Kilbourne Hole (see fig. 28) is stratified sand 
similar to that which underlies the wide surrounding plain, capped 
by a 15-foot layer of lava, which thins out toward the southeast. 
The encircling rim is composed mostly of soft sandstone, strongly 
Rim Rim €. 
rom xine 179-foot = 
dit Bal hee hee Bit eae ; boring epee 
rer Page eee 
Horizontal scale 
re] 1 2Miles 
eu i i i J 
Vertical scale 
° 500 1,000 Feet 
SE | 
FIGURE 28.—Cross section of Kilbourne Hole, 8 miles west of Lanar 
y W 
k, N. Mex. 
- T, Lee. 1, Lava; d, ejected material; Qss, sand 
eross-bedded and including some cinders, fragments of pumice, and 
many angular blocks of lava. A very remarkable fact is that much 
of the cross-bedding slopes toward the hole. It is believed that these 
two holes were caused by a volcanic explosion probably with outburst 
of water. Steam doubtless accumulated in sand under the lava 
sheet until the pressure was sufficient to cause the explosion. 
In the sand penetrated by a 179-foot boring in the Kilbourne Hole 
part of the jaw of a Pleistocene horse was found at a depth of 70 
_ Possibly in material that had caved from the sides of the hole. 
oe aaa, of the boring a large amount of warm sulphur water 
