1388 Reviews—Richmond Coal-field, Virginia. 
and relations of the rocks of Devonian age have not yet been satis- 
factorily determined, but their occurrence is recorded on the 
Mackenzie River, and their presence is inferred in the limestone 
- formation which stretches from the vicinity of Lake Winnipeg to 
the mouth of the Mackenzie, and thence to Baffin’s Bay and 
Grinnell Land. A revision of the fossils from the Mackenzie and 
the Arctic basin is recommended as very desirable. 
An important series of Coal-bearing rocks of Lower Carboniferous 
age (of the so-called ‘“‘ Ursa Stage” of Heer) are distributed in the 
Arctic Archipelago, but no estimate appears to have been formed of 
their thickness, nor indeed of that of any of the older rock-series 
in the Arctic basin. Rocks of Liassic or Jurassic age, of unknown 
extent, are said to occur in the northern part of the Arctic Archipelago. 
The so-called “Miocene” of Greenland and Grinnell Land ‘‘is 
now regarded as equivalent to the Laramie, or at least not newer 
than the Eocene.” The superficial deposits are not dealt with in 
these notes, as the information respecting them is not such as can be 
expressed upon a geological map. A few observations upon glacial 
phenomena are however added. . 
Mr. Coste (pp. 1S—85S) supplies some useful statistical tables, 
with explanations, of the “ production, value, exports and imports, 
of minerals in Canada during the year 1886 and previous years.” 
Mr. G. C. Hoffmann, assisted by Messrs. F. D. Adams, and E. B. 
Kenrick, gives the results of work done in the chemical laboratory 
vf the Survey. There is a full index at the end of the volume. 
Hae WACO Eels 
JII.—Ricumonp Coan Fieip, VirGrnta. 
\HE scanty literature of the Virginia Triassic has lately been 
increased by the appearance of a pamphlet by Mr. William 
Clifford,’ describing this complicated field and illustrating the 
structure by maps and sections. The history, geography, the 
mining methods and difficulties are concisely outlined. There are 
also given some of the characteristics of the rocks of the basin, 
and analyses of coals and natural cokes. As a whole the author 
dwells more on the economic and engineering side, than on the 
purely geologic; but as he devotes some space to a discussion of the 
latter, I would venture to criticize, or at least call the attention of 
others, to his facts and some theoretical conclusions based thereon. 
The statement of first importance, on which many deductions 
rest, is that the strata thin out at the outcrop, or, to give the exact 
words, “the rocks thin out toward the sides of the basin as though, 
during their deposition, the rock material had slid somewhat down 
the steep sides on which it was thrown down.” 
A careful exploration made this year failed to give conclusive 
evidence of such a general thinning. It is true the opportunities 
now of examining the strata are very few—and without doubt there 
1 Richmond Coal Field, Virginia, by William Clifford, M.E., read before the 
Manchester Geological Society, December 6th, 1887. 
