130 
GEOLOGICAL REPORT-THIRTY-EIFTH PARALLEL. 
d’abort! ties marnes rouges qui deviennent de 
plus en plus sableuses et au Camp 28 on a un 
gres rouge tres fin, se desagregeant facilement 
et alors a l’etat de sable rouge un peu argilleux. 
Les couches de gres plongent au sud sous un 
angle tie 10 degres et la direction est ouest, est. 
29 Aout.—Du No. 28 au No. 29, on Denuda¬ 
tion mountain. —Nous suivons les memes gres 
argilleux, rouges, tres-fins; les assises sont 
horizontales, on voit tie beaux exemples tie 
denudations par Teau. Le 1° exemple pres tie 
Spring creek est forme de 8 ou 10 cones, 
ayant 10 pietls tie liauteur; dont M. Campbell 
me donna un dessin. Ensuite a Rock Mary 
8 ou 10 grands cones tronques, au soinmet, 
ayant tie GO a 100 pieds de hauteur. Les 
assises en sont horizontales; c’est du gres rouge 
qui domine, a epaisse stratification; avec les 
alternations tie schistes rouges, plus argilleux, 
se levant par feuillet, avec deux ou trois cou¬ 
ches a la partie superieure de calcaire siliceux, 
gris blanchatre tres dur et qui a preserve et 
forme ces natural mounds. 
Pres tie Camp 29, il y a un tie ces mounds 
avec des colonnes de gres, montrant la stratifi¬ 
cation. Ces gres rouges sont tres-epais, pres 
tie 150 pieds et je commence a soupconner que 
depuis apres Delaware mountain, nous som- 
mes dans le New Red au lieu clu lower car¬ 
boniferous. Pas d’alluvium caillouteux; une 
plaine parfaite. 
30 Aout.—Au Camp No. 30.—Section a l’est 
du camp, a 20 pas: 
Dolomie argileuse_ 6 pieds. 
Gypsum____25 “ 
Grfes, schiste argileux et argile rouge.... 10 “ 
On a d’abord passe pendant 7 miles sur 
ties gres argileux rouges, puis ensuite sur du 
gypse blanc, qui est superpose au gres. Ce 
gypse blanc est amorphe avec quelques vein- 
ules crystallissees; il y a avec des rubans roses; 
les couches sont horizontales; le gypse a 25 a 
30 pieds d’epaisseur. Dans plusieurs endroits 
oil nous passons le gypse est decompose et 
forme des cavernes en zig-zag. L’alluvion est 
du sable rouge, avecquelques cailloux tie quartz. 
Au camp No. 30 on a ties couches tl’une dolo- 
No. 28.—We first find red marls, which be¬ 
come more and more sandy, and at Camp No. 
28 we find a very fine red sandstone decompos¬ 
ing readily into a red sand somewhat argilla¬ 
ceous. The sandstone beds dip to the south 
at an angle of ten degrees, and the trend is 
east and west. 
August 29.— From Camp No. 28 to Camp 
No. 29, or Denudation mountain. —We followed 
the same very fine, red, argillaceous sandstone. 
The strata are horizontal, and beautiful exhi¬ 
bitions of denudations by water are seen. The 
first example near Spring creek is composed of 
from eight to ten cones, having a height of 
about ten feet, of which Mr. Campbell made 
me a drawing. Afterwards, at Rock Mary, 
we saw eight or ten great cones truncated at the 
summit, and being from sixty to one hundred 
feet in elevation. The strata are horizontal, 
and thick strata of red sandstone predominate 
with alternations of red shales, more argilla¬ 
ceous and separating in thin leaves. Two or 
three beds of silicious limestone occur at the 
upper part, of a whitish grey color, very hard, 
and which have preserved the lower strata from 
denudation ; forming natural mounds. 
Near Camp No. 29, there are similar mounds 
with columns of sandstone showing stratifica¬ 
tion. These red sandstones are very thick, 
nearly one hundred and fifty feet, and I com¬ 
mence to suspect that since leaving Delaware 
mountain we are on the New Red sandstone 
instead of the lower carboniferous. No pebbly 
alluvium; a perfect plain. 
August 30.— At Camp No. 30.—Twenty 
steps east of the Camp I find the following 
section in the bank of the creek: 
Argillaceous dolomite.....- 6 feet. 
White gypsum.... 25 “ 
Sandstone and argillaceous shales and red 
clay_____ 10 “ 
The latter is at the level of the creek. 
We passed for seven miles upon red argilla¬ 
ceous sandstones, and afterwards upon white 
gypsum, which is superposed upon sandstone. 
This white gypsum is amorphous, with some 
crystallized veins and rose-colored belts. The 
beds are horizontal, and the gypsum is from 
twenty-five to thirty feet thick. In several 
places where we passed the gypsum is decom- 
