Jemez — AlbuquerqiLe, N. Mex. — Regan. 107 
locate in local craters which penetrate the Cretaceous at var- 
ious places." 
At another place he says :^ 
"Of course the age of these flows is still to be determined, 
though it may safely be placed at an earlier period than that in 
which the river gravels were deposited, that is, earlier than the 
post-glacial or Champlain period." 
Again in speaking of the Albuquerque volcanoes, he says :^* 
"This group of cones is only one of a series of basaltic post- 
Tertiary volcanoes which can be traced along the entire length 
of the Rio Grande in New Mexico." 
Herrick, in these articles, places the age of the volcanoes 
as post-Tertiary ; but has them penetrating Cretaceous strata. 
At a later date he found that the strata along the Rio Grande 
embayment are Tertiary, and then he had the following print- 
ed on a slip in each of the bulletins : 
The reader will kindly substitute the word 'Tertiary' for 
'Cretaceous' wherever in the present article [The Environs of 
Albuquerque] reference is made to the sandy strata underly- 
ing the loess of the river valley." 
The strata that these volcanoes and the great dike penetrate 
are Eocene as we have already noted. This formation over- 
lies the Puerco and Fort Union, and of course, cannot be Cre- 
taceous. 
That these volcanoes are post-Tertiary there is no doubt, 
because the strata immediately underlying the lava cap east of 
San Felipe are Pliocene.* This lava also overlies the Jemez 
marls at Jemez. Another evidence that will aid in establishing 
the age of these flows is this : — while government farmer at 
Jemez, the writer dug a well for the Indian village ; and, after 
digging through more than twenty feet of river filling of Ple- 
istocene age, he found a conglomerate layer separating the val- 
ley deposits from the underlying Pliocene. In this conglomer- 
ate stratum were found boulders of black vesicular basalt, some 
of which would weigh 500 pounds. These boulders on examin- 
ation, were exactly like the basalt in situ on the adjacent Plio- 
cene mesa both in appearance and composition ; and without 
question, were washed into the Jemez Pleistocene lake from 
the top of tlie very mesa. This, it seems to me, is evi dence 
* At this place there are two distinct lava flows separated by a forest 
ground ^vith growth as thick as that now covering the region. 
