438 
SILUKIA. 
Chap. XVIII. 
in both the eastern and the western basins. In the latter the productive Coal- 
measures, occupying four separate fields, the Appalachian, the Michigan, the Il- 
linois, and the Iowa and Missouri, cover a greater area than Coal-measures in any- 
other part of the globe. In the eastern basin the Lower Carboniferous Limestone 
(the Mountain-limestone of England) is wanting ; but in the western it either par- 
tially or wholly supports all the Coal-measures mentioned, gradually thickening 
as it spreads westward ; while, according to Professor Hall, an Upper Carbonife- 
rous Limestone rests upon the Iowa and Missouri or most western Coal-field. 
None of the Carboniferous rocks enter Western Canada; and in Eastern Canada 
only a portion of the Bonaventure formation, equivalent to the Millstone-grit of 
England, presents itself, on the south coast of the peninsula of Gaspe, where it 
emerges from beneath the Coal-measures of New Brunswick and Nova Scotia, 
which in the latter province exhibit, at the Joggins, on the Bay of Fundy, a 
thickness of nearly 15,000 feet. 
" In the western basin there is no apparent want of conformity in the whole 
series of deposits from the base of the Lower Silurian to the base of the produc- 
tive Coal-measures ; but in the northern part of the Illinois Coal-field, the latter 
overlap the Millstone-grit and Mountain-limestone. In the eastern basin there 
is a discordance between the Lower and the Middle Silurian, and also between 
the Devonian and Carboniferous. The undulations, however, which cause these 
discordances, and which affect the formations from the base of the Lower 
Silurian to the summit of the Coal-measures, are all in parallel directions, show- 
ing that the forces which operated to produce the folds continued throughout 
the whole Palaeozoic period, during the latter part of which their influence ex- 
tended far into the western basin, reaching across the Appalachian Coal-field, and 
producing the great Cincinnati anticlinal." 
NovaScotia. — InNova Scotia, the oldest rocksof the Atlantic coast of this British 
Colony consist principally of slates and quartzites, equivalent to the oldest slates 
of Newfoundland, which are known to contain Paradoxides. They therefore re- 
present the lowest portion of the Silurian system. In the southern part of New 
Brunswick, the researches of Professor Bailey and of Messrs. Mathew and Hall, 
have disclosed a similar series, which appears in the vicinity of St. John's, and 
contains species of Paradoxides and Conocephalus. Professor Hind refers to the 
Quebec Lower Silurian group a large portion of the partially altered rocks of the 
northern part of New Brunswick underlying the Upper Silurian of that region. 
The rest of the Lower Silurian series of Nova Scotia is often much meta- 
morphosed, and is the seat of much gold-ore, of which hereafter *. 
The Upper Silurian series of Nova Scotia is represented by considerable areas 
of disturbed and partially altered rocks, which seem to represent the British for- 
mations from the Upper Llandovery to the Ludlow rocks inclusive. They 
differ, however, in several features, from the Upper Silurian of New York and 
other portions of the great interior of North America, but coincide with the 
rocks of this age in New Brunswick and Maine, on the eastern side of the great 
Appalachian line of disturbance f. It is probable that these eastern Upper Si- 
lurian areas of North America (says Dr. Dawson) will be found to present cha- 
racters intermediate between those of the inland area of the continent and those 
of the Upper Silurian of Western Europe. 
* In illustration of these points, see Principal f See Dawson on Silurian and Devonian Rocks 
Dawson's Supplement to ' Acadian Geology,' and of Nova Scotia, Canadian Nat. Hist. vol. v., and 
the Reports on the Geology of Southern New Dr. Honeyman's 'Geology of Arisaig,' Quart. 
Brunswick. Journ. Geol. Soc. vol. xx. 
