98 F ices Limestone in New Mexico. 
tion with large trachytic dykes, extending for miles in length. 
To the north and northwest limestone predominates, and the 
strata are upturned toward the west at an angle of about 20°, 
her er of dislocations by which the w ole 
series of strata are brought up to this angle several times, 
giving rise to a succession of faults on a north and south line, 
of several hundred feet vértical extent. These dislocations 
produce the limestone hills, whose general eastern slopes coin- 
cide with the dip of the strata, while the western declivities, in 
which the edges of the strata are presented, are abrupt, an 
sometimes perpendicular. [Faults occur in other directions 
also, caused by the eruption or intrusion of veins of quartz, or 
other siliceous material, bearing mineral ores. Upon the east- 
ern slope of one of these limestone hills, the celebrated group 
of Sierra mines occurs, from one of which—the Sierra Grande 
—over a million. dollars in silver was taken within a year. 
rt. 
yielding good collections, fe, at one of these the following sec- 
tion was made—the measurements being only picks 
No. 9. Cherty limestone, with irregular flinty m 
In Bar cg of a light gray color and full of éheokdal 
30 feet. 
n color, siliceons in ie ay Ps Np y partings be- 
saae the strata, containi ing shania crinoidal re- 
mains, bryozoa, corals, and piaameds. choetly silici- 
: Thin-bedded bluish limestone, eiadas aie 
ve a ® sale containing crinoids, corals, brachiopods and 
0ZO 
40 feet. 
FVOROS ce co waa aa ce et okt fo 20 feet. 
No. 6. Pinkish to bluish ar iporea hard and granular, = 
nities g a large proportion of sand,.._.____.____- 6 feet. 
5. Finegrained, light yellow. sore “clays with flinty 
no sae kes Seon ee ee ein aie ee ee 15 feet. 
No. 4. Gumi ferruginous limestone, in irregular beds, 
with marly partings, containing corals, crinoid plates 
end etenie, os .g cleo 30 feet. — 
