I go Bulletin of Laboratories of Denison University [Voi. xi. 
sandstone, 35 to 50 feet of brown lignite, 30 to 40 feet of white 
sand with lignite bands, 75 feet of lignite with ferrugineous 
layers and in the latter numerous impressions of deciduous 
leaves and fruits, 10 feet of yellow sandstone, 25 feet of white 
sandstone, 2 feet of ferrugineous sandstone with many fossils, 
25 feet of loose white sandstone and fossils, over 300 feet of 
white and ferrugineous sandstone with few remains. At this 
point is a fault along which lignite appears and also white sand- 
stone as though overthrown, but farther study will be necessary 
to disentangle the confused relations. This we suppose to be 
the upper limit of the exposed cretaceous for the series follow- 
ing dipping to the south east is part of the Tertiary section 
given above. 
The fault mentioned is that of the Isleta mesa monocline 
and may be traced for many miles north and south. A similar 
fault occurs about three miles west of San Ignatio. To the west 
of this the lower part of the series is visible and rises in the 
higher hills to the Punta de la Mesa sandstone but to the east 
of it the lignitic series occupies the entire area. The fauna of 
the sand above the lignite is abundantly illustrated beyond and 
seems to be closely allied to the Punta de la Mesa if not iden- 
tical with it. It is a marine fauna and of Fox Hills age. Thus 
our first impression and the prevailing opinion of geologists who 
have seen these lignites that they are Laramie is overthrown. 
The leaves also, of which a large collection may be made, are 
not identifiable with familiar Laramie species. This same se- 
quence is detected east of the Sandia mountains but we are pre- 
pared to find this series followed by fresh-water or brackish 
Laramie at that place when sufficient exploration is possible. 
Near the Isleta Mesa monocline fault is a bed of shark’s teeth 
and similar remains are found east of the Sandias at the same 
horizon (near Una de Gato). Time does not permit a discus- 
sion of the flora and vertebrate fauna of this formation. 
South-east of the lower end of Prieta mesa there are sev- 
eral isolated mesas which rise from the base-leveled valley like 
islands in a desert sea. One such in particular is a most con- 
spicuous object in the large valley which opens into the Rio 
