LIGNITE WITH FOSSIL PLANTS. 81 
, Feet. 
5. Thick-bedded, light-brown, pink, purple, and banded calcareous sandstones: ------ 50 
6. Orange yellow, and red marls-- +--+ s+++ cece cece cere cere ee eee en eater ates cane 140 
Summit of last section. 
In another butte, between Camps 90 and 91, the trap rests upon the magnesian limestone— 
No. 4 of the last section—and the indurated marls or calcareous sandstones below are pink or 
pure white. In another, east of Camp 91, the same section as that just given in detail is ex- 
posed, with the addition of a stratum of coarse yellow sandstone, the base-rock of the great 
Cretaceous mesa, which, ten miles further north, completely covers and conceals the variegated 
marls. In the upper part of the series represented in the buttes, fossil wood, so abundant 
below, was nowhere observed. The strata contain gypsum in small quantities, and are highly 
charged with salts of several kinds; such as chloride of sodium, and sulphates of soda and mag- 
nesia. The marls are generally more indurated here than below, better deserving the name of 
calcareous sandstones. The variety of colors which they present is also not as great, the ver- 
tical breadth of the color-bands being much greater. These differences are, however, not 
strongly marked, and are somewhat local. 
At Camp 92 we had passed the region of the trap buttes, and found the first outliers of the 
Cretaceous mesa, which, five miles north of us, rose like a huge wall from the plain. We had 
here ascended imperceptibly through all the series of the variegated marls, and the summit of 
a low hill, on which we were encamped, was crowned with the first of the Cretaceous rocks, 
forming a fit terminus to the fine section of the upper marl beds exposed in itssides. The details 
of this section are as follows: 
Feet. 
1. Coarse yellowish sandstone with concretions of oxide of iron, and obscure impressions 
of dicotyledonous JORVOS 0 0s cee 00s oe cae wind dew eh aw oN ONSET ew Wes wena w one 16 
2. Impure coal, alternating with bands of bituminous shale and fire clay, containing 
fossil plants—Clathropteris, Cyclopteris, Sphenopteris, Pecopteris, &c.—all new 
species oe Seige Se ob CES SNES ON SB Cee e eb Cece cee rN ews se gee eRe ees 12 
3. Fire clay and shale.-«.« esceer sees cecesecres ieee ee use wia <0" « sees cies bes 3 
4. Coarse, compact, white, concretionary sandstone --+++++++++++++++* sees teen neers 6 
5. tlvoen yaarl «6c eG obs ove ee hea ees oo ee ae as oes Pe ee eee ere 25 
6. Bright-red marl-----++-+++++++++ + Bn ee ag ee ee eee ne a eS ee ee es 22 
7. White, soft, saccharoidal calcareous sandstone—to base. 
The summit rock is, for the most part, as indicated above, a coarse yellowish sandstone; but 
it sometimes contains small quartz pebbles, becoming a conglomerate. It also includes spheri- 
cal and botryoidal concretions of carb. ox. iron. Many obscure vegetable impressions are 
visible on its surfaces, of which some are those of dicotyledonous leaves, but so badly pre- 
served in its coarse texture as to be scarcely determinable. The coal seam beneath it is com- 
pound in character, consisting of a great number of alternations of coal—some of which is of 
good quality—with bituminous shale and a pure white clay, closely resembling the finer 
varieties of fire clay, associated with the coal seams of the Carboniferous epoch. The details of 
structure of this bed of coal or lignite, are: 
Inches. 
1. Diteminoue aliada 600 = boss 00 Coos sees Oris pre, ECS ero e Speirs coe es ees gees 6 
De Coot sis ede 16 5k Roos Wek os 6 less ee Kee gcsbue sess BSS tne e ce nies puree euee 10 
a ies as 5 say ca Kip re aE EO ee Oe ewes oeiiaie webe & $ 
© Witinthoae whales ok wis bis boss co a ws paw tis wea ee sheen ts a eme eee ae FY? 6 
a i a as Sais wk ts eo Fb ew EE «ee Ee 12 
6. Clay... cece eee cece cent ee cence e cee eees cau gow gine Wipes sien Rees Hees + cae 
7. Bituminous shale---------- i SRoeRS bead ee peewee oe a0 Ek eee z 11 
a ee pines he gi wie aw ie ore eh Leer See 6 
11——-L 
