TACONIC QUESTION IN GEOLOGY. 249 
$ 86. These rocks are not destitute of direct evidences of organic life ; having furnished 
the remains of Eozoon Canadense, which have been described and figured by Dawson. 
Numerous specimens of this have been found in Tudor, “imbedded in an impure earthy 
dark gray limestone, with which, and with carbonaceous matter, the cavities of the white 
calcareous skeleton are filled;” unlike those of the Eozoon from the Grenville series, 
on the Ottawa, which are generally filled with serpentine or pyroxene. Dawson farther 
noticed, in some of the impure dark-colored limestones of the Hastings series from Madoc, 
“fibres and granules of carbonaceous matter, which do not conform to the crystalline 
structure, and present forms quite similar to those which, in more modern limestones, 
result from the decomposition of aleæ. Though retaining mere traces of organic structure, 
no doubt would be entertained as to their vegetable origin, if they were found in 
fossiliferous limestones.” He noticed also, a similar limestone from the same vicinity, 
which is apparently “a finely-laminated sediment, and shows perforations of various 
sizes, somewhat scalloped on the edges, and filled with grains of rounded silicious sand.” 
Other specimens from the same region were said to have indications, on their weathered 
surface, of similar circular perforations, having the aspect of Scolithus or worm-burrows. 
Some of these markings from Madoc were subsequently figured by Dawson, and desig- 
nated “ annelid-burrows,” with the remark that “there can be no doubt as to their nature.”* 
These are as yet known only by a few transverse sections, and cannot, therefore, be com- 
pared with the cylindrical markings referred to Scolithus, and to Monocraterion, in the 
Taconic quartzites and limestones of the Appalachian valley (§ 34, 52). 
§ 87. Brooks described in 1872 an area of rocks in St. Lawrence county, New York, 
lying along the northern base of the Adirondacks. They include the Caledonia and Keene 
iron-mines of that region, and appear as a series of folded strata with a northeast strike, 
resting in apparent unconformity upon reddish Laurentian gneiss. The rocks in question 
consist of granular quartzite, crystalline limestone, and a greenish schistose rock described 
as magnesian. A bed of quartzite is interstratified with the limestones, which include 
tremolite, and are overlaid by the soft greenish grey-weathering schists, to which succeed 
the micaceous and earthy red hematites in lenticular masses intercalated with similar schists 
and masses of quartzite ; a friable sandstone, sometimes conglomerate, overlying the whole. 
White quartzo-feldspathic veins occur in the lower portion of the lmestone. Emmons, 
who described this locality in 1842, and did not observe the lower quartzite, referred the 
overlying conglomerate to the Potsdam, and supposed the hematite, the limestone and the 
greenish rock (by him called serpentine), to be all, alike, erupted plutonic masses. 
The observed thickness of the series, as there exposed, is, according to Brooks, not less 
than 700 feet, and its entire volume probably much greater. Although they were by 
Brooks compared with the Lower Taconic of Emmons, I was disposed, in noticing these 
rocks in 1877, to regard them as a part of the Laurentian. They were at that time com- 
pared with the crystalline limestones, with interstratified quartzites and conglomerates, 
found in Bastard in Ontario.t Farther consideration leads me to suspect that these rocks 
of St. Lawrence county are really an outlier of Taconian. 

* Dawson ; The Dawn of Life, pp. 110, 139, and Hunt, Azoic Rocks, pp. 171-177. 
+ Brooks; Amer. Jour. Science (3) iv., pp. 22-26 Hunt. Azoic Rocks, pp. 218 and 148, and Emmons, Geology 
of the Northern District of New York, pp. 92, 98. 
Sec. IV., 1883. 32. 
