114 C. L. HERRICK 
deep crevices were formed entirely through the acid crust and 
permitted a slow and relatively quiet overflow. This method of 
eruption would account for a considerable degree of fluidity of 
the lava and for the very slight surface disturbance. However 
this may be, the flows of lava, usually of slight thickness, are 
often of enormous extent, and where water has had access to 
the loose materials beneath, the characteristic sal pats results. 
Our way is now across the Jornado del Muerto, the perils of 
passage being greatly reduced by the sinking of wells for 
ranches at various places, though the terrors of a blizzard on 
these barren treeless plains needs but to be experienced to be 
appreciated. Though comparatively arid and seemingly barren, 
the short grass furnishes a good subsistence to many herds of 
both cattle and horses. 
_ Rising by a rather moderate slope from the plain are the 
foothills of the great range which begins with the Sandias east 
of Albuquerque and is continued in a broken line by the Man- 
zanos, the Oscuros, the San Andreas, and the Organs. In the 
Sandias and Manzanos the granite, everywhere lying at the base 
of the stratified rocks, so far as known, in the territory, is 
exposed in an extensive escarpment on the east side of a very 
important fault line and the superincumbent stratified rocks dip 
rapidly to the east. In both the ranges mentioned the rock lying 
upon the granite, or its gneissic or schistose equivalent, is a 
quartzite whose materials seem not to have been derived from 
the subjacent granite, but from a schist or quartz rock which we 
suppose to have been the superficial portion of that series. The 
age of the quartzite, as well as that of the granite, must at pres- 
ent remain a matter of conjecture in spite of poorly preserved 
fossils in the limestone layers found in one or two instances in 
the midst of the granite. Reposing on the quartzite conformably 
in the Sandia and Manzano ranges ts a silicious series with a few 
limestone bands whose fossils seem to be of undoubted Coal 
Measure age. This is followed by a dark conchoidal limestone 
with shales having a fauna similar to that of the Upper Coal 
Measures in Ohio as will be more particularly set forth in another 
