CHAPTER IV, 
OBSERVATIONS ON THE GEOLOGY OF THE ROUTE. 
FROM THE RIO GRANDE TO THE COLORADO CHIQUITO. 
COAL ALONG THE PUERCO.—LAS LUNAS.—BURNING COAL-BED AT CEBOLLETA.—RED "SANDSTONE STRATA.—LAVA.—VOLCANO, SAN 
—BLUE-CLAY AND ¥Fossits.—Covero.—LAVA STREAM.—COULEE.—SMALL CRATER.—GRANITE OF THE SIERRA MADRE.— 
CARBONIFEROUS. —GNEISS.— LIMESTONE ON THE EAST SIDE AT CAMPBELL'S PAss.—SUMMIT.—CARBONIFEROUS.—VOLCANO AT THE 
SOUTH.—TABLE-LANDS WEST OF THE SIERRA MADRE.— MOUNDS IN PECULIAR FORMS.—EL MORO OR INSCRIPTION ROCK.— PERFECTION 
OF OLD INSCRIPTIONS SHOWS THE SLOW WEARING OF THE SANDSTONE.—OJO PESCADO.—LAVA STREAM IN THE VALLEY.—LAVA COVERS 
THE STREAM.—RUINS AT THE SPRINGS.—COAL.—ZUÑI AND ITS VICINITY.—CLIFFS OF WHITE SANDSTONE.—CURIOUS FORMS RE- 
SULTING FROM WEATHERING.—TRADITIONS OF A DELUGE.—F OsSILS.—J ACOB'S WELL.—-DRIFT OF PEBBLES OF JASPER AND AGATE.— 
PUERCO Or THE WEST.—FOSSIL TREE.—RED STRATA.—GENERAL VIEW OF THE EXTENT OF THE TABLE-LAND.—CANON OF THE 
COLORADO PROBABLY IN THE PLATEAU.—VALLEY OF THE COLORADO CHIQUITO.—RED CLAY AND GYPSUM.—FOSSIL TREES SILICI- 
FIED.—DRIFT.—BASALTIC BUTTES. 
Leaving the low alluvial plain of the Rio Grande, and passing westward, the first change in 
the geology is presented at the bluff which terminates the mesa lying between the river and 
the Puerco. The paucity of observations respecting the stratigraphical character of this table- 
land have already been remarked, and its composition noted as far as possible. Of its Creta- 
ceous age there js scarcely*a doubt, both from the evidence presented by the fossils collected 
by Lieutenant Abert at Poblazon, and those found at Galisteo and in the cafions of the Llano 
on the other side of the Sandia mountains. The presence of the white porous limestone on the 
bluff next to the Rio Puerco is additional evidence of the similarity of the strata to those just 
mentioned. Lieutenant Whipple observed the presence of scoriæ and volcanic hills on the 
summit of the high table-lands, and a few miles further south a continuous layer of basaltic 
lava covers the strata and extends from the Rio Grande to the Puerco. 
Coal.—lt appears that coal is found at several points on the Puerco river, and particularly at 
Las Lunas, where, as Lieutenant Whipple observes, it is used by thedragoon blacksmith. This 
coal is said by Mr. Marcou to occur in connexion with greyish-blue clays, which also contain 
fossil trees, and is similar to the clay found at the Galisteo river. It is surmounted by yellow 
sandstone, and the beds dip to the east at an angle of from 15 to 20 degrees. There are no 
specimens of this coal in the collection, and I cannot venture to affirm its age, although it most 
probably is Cretaceous or Tertiary. The nearest coal-bed from which we have received any 
fossils is at the Raton Pass, where Lieutenant Abert collected leaves of dicotyledonous plants, 
which were examined by Professor J. W. Bailey, and pronounced of comparatively modern 
origin. It is much more recent than the carboniferous formation. Coal and jet are also found 
near Lagunas, and, according to Lieutenant Whipple, an excellent bed of coal crops out at 
Cebolleta, and there were accounts of a burning bed about forty miles further north. Captain 
Ker, on visiting this locality, found deep fissures from which smoke was issuing, and which led 
him to mie that the combustion proceeded from a coal-bed.! Lieutenant Simpson also 
found coal about forty-five miles further north, under yellowish sandstone.? 
Before reaching Lagunas, Mr. Marcou notes the occurrence of the red sandstone of the 
“ Trias”” underlying the blue and grey clays and light-colored sandstone. This formation was 
See Lieutenant Whipple’s Report, p. 59. 
* Simpson’s Report on the Navajo country, p. 64. 
