238 
CEMENT MATERIALS AND INDUSTRY. [bull. 2* 
Analyses of Trenton limestone, New Jersey — Continued. 
Silica (Si0 2 ). 
Alumina 
(AljOg), 
iron oxide 
(Fe 2 3 ). 
Lime (CaO). 
Magnesia 
(MgO). 
Carbon di 
oxide (COJ 
40 
29. 78 
8.29 
30. 10 
2.13 
41 
2.64 
.82 
• 53. 88 
.72 
42 : 
27.08 
8.76 
31. 00 
1.83 
43 
11.72 
1.00 
47.37 
2.06 
44 
5.46 
1.83 
49. 38 
2.26 
45 
22.72 
8.15 
35. 78 
1.86 
1 
1-5. Murphy farm, near Carpentersville. 
6-7. One mile southwest of Pattenburg. 
8. Near Branchville. 
9. Near Myrtle Grove. 
10. Near Swartswood station. 
11. Swartswood village. 
12-13. Northwest of Stillwater. 
14. Near Jacksonburg. 
15. Hainesburg. 
16. Columbia. 
17-20. Near Beaver Run. 
21-22. Near Monroe Corners. 
23-25. Near Lafayette. 
26-30. Near Newton. 
31-33. Near Drakes Pond. 
34. Three miles southwest of Newton. 
35-36. Near Huntsburg (Hunt's mills). 
37-40. Springdale. 
41. Swayze's mills. 
42. Near Hope. 
43-44. Sarepta. 
45. Near Belvidere. 
The Trenton limestone can be readily distinguished from the magi 
nesian Kittatinny limestone by the following points: (1) The TreiHj, 
ton is usually fossiliferous. Some surfaces are covered entirely wi j 0] 
imprints of shells. Beds otherwise unfossiliferous usually conta L 
crinoid stems, which are best seen on weathered surfaces as sma 4 
disks, often with a hole in the center. The fossils of the Kittatinriik 
limestone are so few and so obscure that only an expert can detej m 
them, so for practical purposes the formation can be considered unfosiL 
siliferous. (2) The dark blue or black color of the Trenton weather iL 
to a light gray-blue, entirely unlike most of the Kittatinny beds. Soil 
too, the rough, knotty character of the bedding and of the weathere 
slabs is characteristic of the Trenton limestone. (3) A drop of hydrji 
chloric acid will cause the Trenton limestone to effervesce vigorously 
whereas the cold acid dropped on the Magnesian limestone acts weak! 
or not at all. (4) The Trenton may usually be recognized by its pos: 
tion. It lies on top of the Kittatinny limestone and beneath the slate 
which is the next higher formation, so that its outcrop forms a narrow 
strip between the wider belts of these rocks. It is not found, how J 
ever, in this position where faulting has brought the slate against thl 
Magnesian limestone, and it is sometimes faulted into the midst of thU J 
[ 
