19S 
GEOLOGY OF NORTH CAROLINA. 
beneath and, for the most part, concealed. Near market street also in 
the middle of the city beds of shells crop out in the cellars. It is used to 
some extent as a dressing for the streets, and serves as a cement to give 
solidity to the mobile sea sand of which they are composed. 
Nos. 29 and 30 are the upper and lower strata of an outcrop at Mr. 
Armstrong’s, 4 miles north of Rocky Point. Nos. 31 and 32 are from 
Wm. Thompson’s, a few miles west of Rocky Point, — upper and lower 
strata ; 33 and 3d from J. McIntyre’s, 6 miles west; the latter remarka- 
ble for its large proportion of phosphoric acid. Marls of similar quality 
are found still further "west, on Moore’s Creek, at Mrs. F. A. Colvin’s and 
other places. They have been used to some extent in many portions of 
the upper end of the county, and always with decided advantage. The 
reason will be obvious on an inspection of the above analyses, all of which 
show, besides a large percentage of calcareous matter, notable quantities 
of potash, magnesia, phosphoric acid, and most of them, of sulphuric acid 
also. 
Blue Marls of Sampson and Duplin. 
35 
36 
37 
38 
Silica, 
. . . 33.64 
38.23 
29.3S 
55.99 
Oxide of Iron and Alumina,.. . . 
. . . . 3.17 
5.15 
4.27 
7.4S 
Lime, 
... 33.58 
29.19 
33.35 
16.46 
Magnesia, 
. ... 0.71 
0.5 S 
0.93 
1.73 
Potash, 
. .. 0.31 
0.75 
0.52 
0.91 
Soda, 
.... 0.32 
0.04 
0.13 
Phosphoric Acid, 
0.61 
1.40 
0.39 
0.32 
Sulphuric Acid, 
.... 0.79 
1.57 
0.89 
1.56 
Carbonic Acid, ... ........... 
...26.16 
21.41 
26.37 
13.67 
Organic Matter and Water, 
0.71 
1.68 
377 
l.SS 
No. 35 is from the farm of J. C. Pass, a mile and a half west of Fai- 
son’s Depot. This is a very good marl and abounds in shells. It is of 
an ash color and apparently exists in large quantity. Another well known 
outcrop in the same neighborhood is at Dr. Thompson’s, whose crops are 
a sufficient evidence of its value. It is found again in the railroad cut 
near the depot, and a few miles south on the railroad ; and at Giddens- 
ville, 5 or C miles northwest, the marl is within a few feet of the surface ; 
a specimen from this point gave 49.80 per cent, of carbonate of lime. 
JNo. 54 is from the farm of Jas. King, some 10 miles from the depot, 
southwest. Marl is found over the whole of his farm, even in the well at 
