On the Secondary and Tertiary Formations. 335 
Several springs come out at its edge, which bring up small fos- 
sil shells and pieces of coral. Among the shells, which are gene- 
rally very imperfect, may be recognized the Pecten membranosus, 
a Cardium, and others common to the same formation in New 
Jersey. The water seems well adapted to the recent Planorbis 
trivolvis, Physa heterostropha, and Paludina i integra, which in- 
habit it in profusion, and also to the luxuriant water-cresses, 
which equally abound in it. Around the limestone is a deposit 
of calcareous marl of a light yellow color, affording a very con-- 
venient and rich natural manure; but it has been entirely neg- 
lected as well as the limestone, the little lime required for the 
country being brought from Thetnaston; Maine, although they 
have enough of the rock, wood at the expense of cutting it 
only, and a suitable enaiatate, for kilns scattered through this 
region... This stone belongs: to the same formation, and has been 
selves with their own lime. prrecamele: Seat ais. ames Messy 
_ Not far from this place, is that - . ality in Duplin’ 
county, called the “ natural well.” idee west of the 
rail-road, (forty-seven miles from Wilmington, ) on the road from: 
Eenenesilia to Elizabeth, Baden county. Before reaching: it, 
One may notice by the side of the road a large sink-hole, fifteen’ 
feet deep, overgrown by trees and bushes; a little beyond this, a 
path turns off to the left to the cabin of a Mr. John Smith, with- 
in two hundred yards of which, in the woods, is the well. It is 
a large circular basin, about twenty yards across and sixteen feet 
deep to the surface of the water; its banks are nearly vertical, 
or the strata are entirely obscured. by the loose sand, trees 
shes tl covered them. yin one narrow spot, 
es section may be obtained and specimens. col- 
lected. The soil, which is sand and yellow loam, a little clayey 
at bottom, is from three to four feet thick. It rests on the shell 
marl; which is about four feet thick, and under this isa tough 
blue clay from six to eight feet thick, overlying a sandstone like 
the clay-in color, the lowest visible rock. The marl consists 
entirely of shells, and. fragments of shells, with a very small 
reg ane oh " oe ie aE 
