208 
GEOLOGY OE NORTH CAROLTNA. 
many miles. The two 
anal} 7 ses following, from the 
New Jersey Report 
for 1863, will show the 
comparative excellence of these marls 
and ours. 
1 
2 
3 
Silica, . . . . 
50.20 
65.53 
Oxide of Iron and Alumina, 5.91 
5.33 
11.67 
Lime, 
15.30 
19.71 
2.71 
Magnesia, 
0.69 
0.50 
2.65 
Potash, 
Soda, 
0.97 
0.5$ 
0.63 j 
1.12 
Phosphoric Acid, 
0.45 
0.70 
2.00 
Sulphuric Acid, 
. . .3.56 
2.09 
6.70' 
Carbonic Acid, 
9.09 
15.05 
Organic Matter, 
2.12 
Water, 
2. SO 
6 15 
5.17 
Of the first two of these marls, Prof. Cook says, that the land in the 
neighborhood was exhausted, so that it was too poor for wheat, and 
some of it even for rye. “ Forty years have elapsed, and competent au- 
thorities estimate that the land has increased in value tenfold. The whole 
country about this marl outcrop has become a wheat-growing region in- 
stead of raising poor crops of rye.” Its “ effects are said to be visible 
for 30 years.” There is a large trade in these marls. “The general 
practice is for the seller to dig it out and sell it from the bank.” “ The 
average price per ton-load is about fifty cents, though at some pits it is a 
dollar a load. “ The pits are generally kept free of w T ater by pumping, 
which is done by water power or steam, or the water is syphoned off.” 
On comparing these analyses with those of the North Carolina blue 
marls above given, it is obvious that they are hardly up to the average 
and much inferior to a very large proportion of them. And yet the 
difference in the estimation is immense, and on the wrong side. The 
third of the above marls is so poor that it would hardly rank with the 
■most inferior kinds here, that are thought to be scarcely worth handling. 
But in order to furnish the means of forming a more definite and pre- 
cise notion of the value of these deposits, absolutely and relatively, the 
following table is added. It is founded on the estimates which are ar- 
rived at in other parts of the world, the English tables being the basis. 
The values for phosphoric acid and potash are adopted from Prof. Cook’s 
table, as they seem reasonable, and for the purpose of comparison ; the 
former no doubt existing as phosphate of lime and the latter as silicate 
of potash. 
