Art. V.3 Herrick, Geology of New Mexico, 109 
the north which is affected by its forcible intrusion in such a 
way that it dips away from the dyke on either side. At this 
place the freestone is filled with impressions of a single species 
of mollusk. The exposure is as follows : gray, fissile, earthy 
shale, 75 feet, the upper part being carbonaceous and partings 
of flags occurring throughout; thin-bedded grey shales, 75 feet; 
sandy shale with flags, 50 feet; freestone with fossils, 140 feet; 
crystalline white sandstone, ten to twenty feet. 
Between this amphitheatre and San Antonio the series seems 
to be twice repeated by faulting and between the later place 
and Tijeras there is a series of hills containing the J ura-triassic. 
7 . 
THE CERRILLOS AND ORTIZ AREA. 
About six miles west of Cerrillos on Galisteo creek a nar- 
row zone of the red J ura-triassic shales and sandstone outcrops. 
The dip is here east and northeast perhaps 25 degrees. A care- 
ful search discovered no fossils. North of the creek the Creta- 
ceous strata rise to a height of about 375 feet above the track. 
The section at this place is as follows : 50 feet of red shale and 
sand capped with hard red sandstone, then 175 feet of white 
sandstone of varying consistency, 75 feet of chocolate shales 
with concretions in bands, followed by twenty feet of sandy 
white shales with a band of white sandstone about three feet thick 
below and a somewhat thicker one above, 30 feet of sands and 
shales and at the top 25 feet of indurated sandstone or quart- 
zite with conglomerate. The base of this series may be Jura- 
triassic. Passing eastward, after what seem to be two partial 
repetitions of this section by faulting, we encounter a section 
with quartzite at the base which passes into white sandstone, 
then 20 feet of bluish black shale, a zone of red calcareous 
concretions and 25 feet of dark fissile shale and 15 or 20 feet of 
yellow sandstone. After crossing a deep valley the following 
section is encountered ; 1 1 5 feet of gray shales and thin flags 
with numerous Cretaceous fossils, covered with a sheet of 
about ten feet of what seems to be a basic eruptive rock similar 
to that covering a great deal of the region about Cerrillos. 
