TERTIARY FORMATIONS, 179

Virginia was a land area during the deposition of the Trent, and the
formation did not extend much farther north than its present position.

Structure—As is true of all the strata of the Coastal Plain, the
structure of the Trent formation is extremely simple. The beds in

some places are practically horizontal, but, in general, dip.toward the
ocean at the rate of about 3 to 5 feet per mile.

Detailed Sections.

Spring Garden Landing, Neuse River—A hard white Eocene lime-
stone rises in the low river bank about 31% feet above the level of the
water in the river. The limestone contains many fossil casts, the shell
substance is entirely gone, and the cavities are usually filled with cal-
cite crystals. In places the cavities have not been filled. This rock
has been used for buhrstones.

The fossils present, though numerous, are not varied. .

Above the rock occurs thinly laminated drab clay and gray sand of
Pleistocene age with an average thickness of about 10 feet.

In the river bank the Eocene is well exposed.

SECTION ROCK LANDING, NEUSE RIVER.

Pleistocene: \ Fret.
Yellowish-brown loam and sand with a few small pebbles, princi- 4
pally concealed by vegetation........... a UA Sen era aah peli oy Oe

Eocene (Trent) : - F

Hard, firmly indurated white limestone filled with casts and
moulds of fossils, the shell substance haying been largely re-
moved, leaving cavities which, in some places, have been filled
with calcite crystals. Grades into next member............... 414

Less firmly indurated limestone containing pockets of brownish-
gray sand, many hard nodules of brown sandstone bored by
Teredo, and fossils, many of which ‘preserve the shell struc-
ture, especially Pecten, Ostrea, and Hchinoids. Grades into

Imembers -PelOw- AUG AWOVEs. oo oa. sei ee Reb wea ene eecks if
Loose brownish to yellowish-gray quartz sand with many small
black grains, principally magnetite; contains no fossils, Ex-

POROG: 50 WHEE S 1 OOMO US Swany eae cee ueuiie ore oder hud caeetion 5

‘The indurated layer in the above section is the one exposed at Spring
Garden Landing, and it also outcrops along many small streams south
and southeast of Rock Landing. About 2 miles south of Rock Landing
it outerops as a continuous ledge about 4 feet in thickness at the head
of a small stream for a distance of about 14 mile. Many excellent
springs issue from beneath it.

Biddle Landing, Neuse River—Here there is a thickness of about 20
feet of Eocene sandy limestone exposed. In places the gray calcareous