TABLE-LANDS—SANDSTONE AND FOSSILS—ZUNI. 41 
table-mounds, by the erosion or cutting of running water, which separates them from the 
mound or bluff. The degradation or wearing of the sides proceeds more rapidly than the top, 
so that they become gradually narrowed down to slender shafts, without becoming diminished 
in height. They are beautiful monuments of the gentle but persistent action of the weather in 
that climate. 
NATURAL PINNACLE AND ARCH, ZUNI, 
The table-lands both north and south of Zuñi are dotted at intervals by remnants of the 
upper strata, standing alone with flat summits. The yellow and white sandstones appear to 
be gradually broken away and denuded from this point westward, becoming less continuous and 
not presenting a thickness so great as farther east. 
ossils.— Between Camps No. 71 and 72, Mr. Marcou found some fossil-shells of the genus 
Gryphea, and the trail rose from the bed of the Zuñi river to the top of the table-lands, where 
the light-colored sandstones were again met and crossed. This plateau is between the Zuiii and 
Puerco rivers. 
Jacob's Well.—At Camp 73 a remarkable well was found. This is described by Cap tain 
Whipple as a funnel-shaped depression, about three hundred feet wide at the top, Ae? one 
hundred and twenty-five feet deep. Water is found at the bottom. It was evidently not the 
work of art, as there was no vestige of any removed earth around the pit. Several other pits 
of a similar character were also seen in the vicinity. It is most probable that these depressions 
are caused by the caving in of the ground over cavities or caverns, caused either by the flow of 
subterranean streams or the gradual solution of thick beds of gypsum. 
Mr. Marcou notes the occurrence in this vicinity of pebbles of red and yellow jasper. This 
reminds the geologist of the ‘‘ drift," found on the surface of the Llano and table-like hills 
on the east of the Rio Grande valley. 
Puerco of the west.—The Puerco river, like the Zuñi, rises near the western base of the Sierra 
Madre, and flows in a valley with vertical walls of sandstone strata towards the Colorado 
Chiquito. After passing Jacob’s Well the survey descends from the table-land over the reddish 
sandstone strata to the bed of the stream. On this slope the alluvial Se of agate, jasper, 
Tin and a fossil tree, were found. 
Up to this point the upper or Cretaceous strata have been found to ovre ian ime 
De: p pipe Ee but now broad areas are seen, comp d strata 3 
6 t 
