MARYLAND. 
Analyses of Trenton limestones from Maryland. 
181 
Silica 
(Si0 2 ). 
4. 73 
4. :;i 
99 
.. 10 
.20 
.50 
6.00 
Ahnniii; 
(ALA,). 
Iron oxide 
(Fe 2 3 ). 
1.40 
.90 
0. 20 
.16 
0. 25 
Trace. 
.10 
.10 
.20 
0.2 
7.2 
.6 
Trace. 
.5 
1.7 
.3 
.9 
1.2 
2.2 
1.5 
.0 
1.2 
1.3 
.2 
Lime car 
bonate 
(CaC0 3 ). 
93. ."-7 
81.97 
97. 32 
00. 71) 
97. 00 
98.50 
90.70 
94.6 
86.0 
98. 3 
99. 5 
92.0 
92.3 
94.5 
90.4 
97.5 
95. 3 
96.0 
99.9 
98. 5 
96.2 
99. 3 
Magnesium 
carbonate 
(MgC0 3 ). 
0.30 
13.00 
2:03 
2. 86 
2. 50 
.80 
3.00 
5.2 
6.8 
1.1 
.5 
7.5 
6.0 
5. 2 
.7 
1.3 
2.5 
2.5 
.1 
.3 
2.5 
.5 
,2. Walkersville, Frederick County. II. J. Patterson, analyst. Twentieth Ann. Kept, U.S. Geol. 
rvey, pt. 6, p. 401. 
i, 4. Frederick, Frederick County. J. O. Hargrove, analyst. Ibid. 
i. Beaver Creek, Washington County. J. Higgins, analyst, Third Kept. Maryland Agric. Chemist, 
135. 
i. Williamsport, Washington County. J. Higgins, analyst. Ibid. 
'. Pleasant Valley, Washington County. J. Higgins, analyst. Ibid. 
I. 9. Frederick, Frederick County. J. Higgins, analyst. Fifth Kept. Maryland Agric. ( 'bemist, p. 78. 
10-12. Unionville, Frederick County. J. Higgins, analyst, [bid., p. 80. 
13-15. \V Isboro, Frederick County. J. Higgins. analyst, Ibid., p. 77. 
6, 17. Dollyhide Creek, Liberty, Frederick County. J. Higgins, analyst. Ibid., p. 80. 
L8-22. Near Liberty, Frederick County. J. Higgins, analyst. Ibid., p. 81. 
M ETA M ( >K I ' I r I ( ' T 1 1 K NT( > N 1 . 1 M KNT< > X KS. 
In eastern Maryland, particularly in Carroll, Baltimore, and Howard 
mnties, a number of areas of highly crystalline limestones or " mar- 
fes" occur. It seems probable that many of these crystalline lime- 
ones are of the same age as the Cambro-Ordovician limestones farther 
est, having merely assumed a crystalline condition as the result of 
sing subjected to pressure and heat. 
In composition these crystalline marbles vary, just as do the unmet- 
:norphosed Cambro-Ordovician limestones. The Cockeysville marble, 
