BA LIMGNITE AND LIMESTONES—GILPIN. 
50 to 500 yards from the Silurian slates, runs a bed or series 
of beds of Gypsum. This is prominently exposed at Glengarry, 
West Branch, Springville, McLellan’s and Irish Mountains, and 
Sutherland’s River. Between the Silurian and the Gypsum are 
numerous beds of Limestone, the thickest continuous one that I 
have seen being about 135 feet. The total thickness must be 
very much greater, as the section of denudation already referred 
to, at iBrideevalles appears to hold an Bae) unbroken series of 
Limestone beds. 
The points of contact of these Limestones with the older slates 
afford many instructive sections bearing directly on the subject 
matter of this paper. One of them is as follows :—A bed of 
ferruginous Limestone rests on the Silurian slates, having at the 
point of contact a breccia of clay slate, cemented by a Calcareous 
paste. The fragments of slate are very close together in the im- 
mediate vicinity of the slates, but become more and more scat- 
tered until they disappear. Other beds of Limestone, shale and 
Gypsum complete the section. 
In another section the ferruginous Limestone is replaced by a 
dark Carbonaceous one folding many fossils, followed by 100 
feet of ordinary gray Limestone. 
In another the pebbles appear rounded and the change to 
Limestone is quite abrupt. These Limestones are worn into 
~ caves and sink holes, frequently large enough to engulf good 
sized brooks for a portion of their course. 
There is also another point to be considered in connection with 
this set of Limestones. Near Sutherland’s River, in the same 
Lower Carboniferous horizon, is exposed a bed of Spathic ore, 
associated with Limestones and Gypsum, and only a few yards 
distant from the Silurian rocks. Fragments of Spathic ore occur 
in French River, one mile to the east. And on Sutherland’s River, 
MeLellan’s Mountain and Brook, East and West Rivers, frag- 
ments of Spathic ore are also found in connection with this set 
of Limestones and Gypsums; and at one point on the East River 
there is exposed asemi-spathose Limestone holding 24.1 p.e. of 
Carbonate of Iron. Eight analyses of the Limestones of this dis- 
trict, made by myself, gave on an average 3 p. c. of this mineral. 
