 LITHOLOGICAL CHARACTERS OF THE STRATA. | 167 
ance, being sometimes comparatively quiet, and at others, thrown into currents. The thick 
beds of sand also present evidences of variations of current, both in direction and velocity. "The 
inclined stratification, called diagonal stratification, is very common, and in many cases is beau- 
tifully shown by multitudes of the finest layers of sand, inclined in different directions, as shown 
in the sectional representation of the strata at e, Geological Sectiens, Sheet I. : 
The distinctness of these lines is caused by the difference in the sizes of the grains of sand, 
and by slight differences of the materials, which have become stained yellow and brown since 
they were deposited by the infiltration of ferruginous water from the superincumbent strata. 
These examples of diagonal stratification were found in the lower portions of the strata, in the 
hill-sides near the level of the creek. They were thus probably about eight hundred feet below 
the higher beds of the formation. The diagonal stratification of the lower beds, and other 
facts about to be mentioned, indicate that their deposition took place in comparatively shallow 
water, 
The mineral constitution and alternation of the strata will be better understood by the exam- 
ination of the section which has been referred to. This represents the succession of the strata 
in a vertical height of one hundred and sixty-two feet, and it is drawn on a scale of twenty feet 
to an inch. 
The hill in which this order of the strata occurs is near the spot which was occupied as the 
Depot camp, and is on the south side of the creek. The upper parts of the series were not ex- 
posed to view, and are not included in the section. It is, of course, impossible to represent, 
within the limits of this section, the numerous lines of the strata; they are innumerable, and 
very regular; most of the layers, among the finer materials, being as thin as paper. 
The following is a brief description of the principal beds in the series, in their order of suc- 
cession, from the level of the creek upwards. The letters refer to corresponding divisions of the 
section. ` 
‚SECTION OF THE STRATA AT OCOYA CREEK. 
Feet. 
% ۳2 friable, gray sand, stained with lines of oxide of iron, and enclosing nodules of various sizes encased in 
xide of iron 2.0 
b. adt in thin layers, stained with oxide of ir 0.6 
ge and sand, enclosing casts of fossils, cile stratified, and all strongly cemented with sesquioxide of _ 
0.7 
c. Band, Gained by iron ; includes a thin layer of pebbles 20 
d. Casts and moulds of fossil shells in sesquioxide of iron, gravel and sand ; layers oblique 1.4 
e. Fine gray sand, cross stratification distinct, contains nodules of clay 240. 
f. Fine gray sand, be e — layer of — een stratum is peur hid) 41.0 
. 9. Argilla quarte to three inches in diameter 1.0 
À. Fine sand, with RER layers of oxide of iron 4.0 
Fine sand, with small, spherical and ellipsoidal masses of di Thin layers of charcoal, in 
fragme: 
nts 
i. Fine white sand, derived from pumice-stone, with intercalated layers of pumice in nodules and in powder... 25.0 
J. Pumice-sand, or — ashes, very fine and white, in thin strata 15.0 
k. White clay and fine san 2.0 
l Sand, with clay ee 20.0 
m. Gravel and pebbles, with sand : 1.0 
n. Gray sand, with layers of pebbles ا‎ 
Sandstone and layers of pebbles crop out at intervals on the side of the hill for fifty or sixty 
feet above the last stratum described. Higher than this, a harder sandstone and a layer of con- 
glomerate is found. Still above, to the tops of the hills, the strata are completely obscured by 
