Chap. X7III.] UPPER SILURIAN— ARCTIC REGIONS. 
441 
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von Buch. ; with Upper Silurian forms of Ortho- 
ceras, Murchisonia, Strophomena, Orthis, Rhyn- 
chonella, &c., besides Encrinites, and very nume- 
rous Corals, including the Chain-coral, Favo- 
sites Gotlandicus, F. cristatus or polymorphus, and 
several other species characteristic of this divi- 
sion of the Silurian system, and, as might be ex- 
pected, of American rather than European types. 
The same inference has been drawn by the ge- 
ologists who have surveyed the rocks, and the na- 
turalists who have examined the fossils, of the 
northern edge of the great gneissic region of the 
Laurentide Mountains. Their conclusion is, that, 
whilst on the south side a succession is seen from 
the crystalline strata into a copious and diversified 
Lower Silurian, as above explained, the northern 
side of the Hudson's Bay territory is chiefly occu- 
pied by Upper Silurian limestones *. This infer- 
ence is founded on the occurrence, at the base of 
the whole fossiliferous series in that district, of a 
profusion of Corals, several of which are charac- 
teristic of the Niagara and Onondaga Limestones 
(Wenlock or Dudley), together with the Trilobite 
Encrinurus punctatus, the Shells Atrypa reticularis 
and Pentamerus oblongus, with several other Mol- 
lusca (Ormoceras &c.) indicative of the lower 
portion of the Upper Silurian group. Now, as 
in all the vast extent of land that has been sur- 
veyed in the Polar circle, no trace of the Lower 
Silurian formations has yet occurred f , the inference 
seems justifiable that during that period the Polar 
land, or all the region north of the Laurentide 
dome, was raised above the water, and was sub- 
sequently depressed to receive successively the 
Upper Silurian, Devonian, Carboniferous, and even 
some Secondary deposits J. 
* Sir W. Logan has found that these limestones at the head 
of Lake Temiscamang include enormous blocks of the sandstone 
on which they rest ; so that, in all probability, they are littoral 
deposits, and Pentamerus was not a deep-sea shell. 
t The two highly enterprising Arctic expeditions undertaken 
through the zeal and munificence of American gentlemen, the 
first under Dr. Kane, the second under Dr. Hayes, which 
reached the most northern lands ever explored, have quite con- 
firmed the view which is taken in the text. In the first of these 
expeditions, some headlands ranging far away to the north-eastern 
side of Kennedy Channel (beyond Smith Sound) were sighted to 
the north of Grinnell Land. Dr. Hayes has since penetrated to 
a bay in lat. 81° 35', which he has most properly named after 
Lady Franklin. From the adjacent cliffs he nas collected nu- 
merous fossils which, having been examined by Professor Meek, 
prove to be all Upper- Silurian forms. Dr. Hayes has named 
one of the northernmost of the larger promontories Mount 
Murchison ; and, as the author of the ' Silurian System,' I am 
naturally gratified by this distinction. (See his work, 'The 
Open Polar Sea,' London, 1867, pp. 72, 340 et seq.) 
I Permian limestone has been found as a drifted block at 
Spitzbergen, but has not yet been observed in the Arctic regions 
of North America. Certain Secondary limestones, charged 
with Ammonites and bones of Ichthyosauri, occur in the most 
northern latitudes explored. See Belcher's 'Last of the Arctic 
Voyages,' vol. ii. pi. 35; M'Clintock, Journal of the Eoyal 
