Geological Rccojuwissancc in N. M. — Hcrrick. 337 
mian, beneath which is the large sandstone and quartzyte se- 
ries known as the Manzano or Permo-carboniferous sand- 
stone series. Still beneath is the limestone portion of the 
Carboniferous. These strata are shown, though much dis- 
turbed, in the foot hills of the Jemez range, especially on the 
west side east of the fault line extending along the base. 
North of the amphitheatre the strata lie parallel to the range 
and above the gypsum, which is now at the bottom of the ex- 
posure, is tlie Jura-triassic. We have found it possible to 
distinguish in this part of the series two portions which usu- 
ally differ in color and in lithological character. The lower 
member or middle division of the red series, that may in gen- 
eral be compared to the Triassic and has been so identified by 
Cope and Newberry, though they w-ere apparently not aware 
of the relations of the Permian, has a prevailingly darker color 
and has been termed the chocolate beds. The thickness of the 
chocolate beds is not much over 500 ft. and the\' are followed 
by about 250 feet of yellow sandstone or quartzyte, which 
may be considered the basal members of the vermilion or up- 
per beds. The chocolate beds in other parts of the region are 
altered to indurated quartzytes characterized by the presence 
of light spots of variable size. The upper or vermilion beds 
are composed of bands of indurated sandstone with shales of 
bright vermilion or green color intervening. Where typically 
developed this is a very characteristic portion of the series. 
At the top of the red series is a band of variable width 
composed of pulverulent white and yellow sandstone, which 
here marks the base of the Cretaceous. It appears that in 
the Nacimiento region as well as in the Rio Puerco valley 
the Dakota group is entirely absent. West of the Nacimiento 
amphitheatre and continuing southward the Cretaceous ap- 
pears in successive step-like escarpments which are cut 
through by the western and southern tributaries of the Rio 
Salado. 
Through these strata a series of basalt necks has broken 
like a black T)imply eruption dotting the area west of the Rio 
Salado. Erosion of the soft strata has tended to leave the 
volcanoes isolated from their surrounding flows in the form 
of basalt "necks" fully described in the report on this region 
by captain Dutton. The most north-easterly of these necks 
