Art. IV.] Herrick, Geology of New Mexico. 8i 
site beneath the trachyte, Merritt and other mines; 26. beds of 
kaolin from decomposition ot andesite and trachyte ; 29. Blue 
Canon; 30. Rio Grande smelter; 31. spring; 32. spring and 
mill; 33. ranch; 34. clay. 
2 * 
THE LIMITAR VOLCANO. 
Limitar mountain is a member of the range bordering the 
Rio Grande on the west that lies north of the Socorro moun- 
tains. The interval between them is filled with lower ridges of 
the same materials as are seen in the main mountains, chiefly 
trachyte flows probably from fissures in the of axis upheaval. The 
stratified rocks are less disturbed. This mountain is about five 
mills from the river and directly west of the town by the same 
name so that it is easily visible from the Santa Fe rail road. It 
may be distinguished by the oblique band formed by a section 
of tilted limestone laid bare during a late explosion of the vol- 
cano. Between the river and the base is a series of sandstones 
and crags which may be of Pleistocene age or recent, while 
nearer the base are what may prove to be remnants of Creta- 
ceous sands and shales with a sharp dip to the west and inter- 
bedded with ancient basalts. It would appear, however, that 
the later fragmental series is only mediately related to the erup- 
tives which furnished their materials, for at the foot of the cores 
of eruption we generally find a d.fferent class of fragmentals. 
In the early history of our volcano, as well as at intervals sub- 
sequently, there were periods of explosive activity or else the 
products of eruption were cast, while still hot into the sea, there 
to be shaken up violently and detonated by the sudden cooling. 
There is evidence that both of these methods of comminuting the 
flows were in vogue at different times. Thus in some cases the 
resulting product is a coarse breccia with angular fragments and 
a very small amount of sand in the interstices, while in other 
cases, the binding material is of the substance of the flow which 
has caught up the exploded fragments in its course. Some are 
veritable talus-conglomerates within or near the crater itself, 
while others are but the selvages of anarachactic or narrow in- 
