The Mesozoic Series of Neio Mexico. — Marcou. 223 
now. On professor Stevenson's map, the Dakota group — the 
only Cretaceous group I shall refer to — occupies all the mesa, 
from its extreme limit or rim, from near Lamy Junction to 
opposite San Miguel, extending west almost to the village of 
Oalisteo. On my map the Dakota Cretaceous is limited to 
only three miles north, east and south of Galisteo ; and all 
the vast mesa from its rim to only three miles from Galisteo 
is occupied by the Jurassic rocks, with three outcrops of Trias 
inclosed, no one of which is marked on Stevenson's map. 
Professor Stevenson has limited what he calls a "linear out- 
crop of Jura Trias," 700 feet thick, to the perpendicular cliff, 
which begins at the rim of the mesa, and follows all the 
anfractuosities of the mesa wall. It is limited to a sort of 
stone wall, of a serpentine-like form, unknown until now in 
the world, for two great systems of strata, the Jurassic and 
the Triassic, combined in one, almost horizontal or very 
slightly inclined. On my map the Trias, 1,500 to 2,000 feet 
thick, occupies not only the mesa-wall, but extends all over 
the valley of the Santa Fe stage road, and also down the 
whole valley of the Rio Pecos as far as south of Antochico, an 
area which has been colored by professor Stevenson as belong- 
ing to the Carboniferous. 
As to the Jurassic system at Canon Blanco, at Cuesta, and 
opposite old Pecos church, the thickness is about 250 feet and 
very likely more, in its extension over the mesa. And both 
together, Jura and Trias, instead of being a serpentinuous 
linear outcrop as marked on professor Stevenson's map, on 
the contrary occupy a vast surface, as I have colored them 
on my map ; and they are not confounded in a single system 
anywhere. 
On my map the Carboniferous is limited to the north of the 
Santa Fe stage road, and I have placed the Trias in direct 
contact with the Azoic or crystalline rocks, just north of 
Lamy Junction, where the stage road crosses the crystalline 
rocks area. On professor Stevenson's map there is no contact 
of the Trias with the crystalline rocks, and we see instead a 
large band of Carboniferous surrounding the crystalline rocks, 
which certainly does not exist at the stage road crossing. 
West of Pecos village I have delineated on my map the Car- 
boniferous approximatively, because I was not there, and 
what I know of it was obtained in looking over from the top 
