622 



SCIENCE. 



[N. S. Vol. V. No. 120. 



been recognized. The Carboniferous or Cache 

 Creek series is 12,000 feet thick, one-third 

 limestone. Its character is lilie that of the 

 corresponding limestones and quartzites of cor- 

 responding age observed in our Fortieth Parallel 

 Survey. The Triassic, or Nicola group, occupies 

 a considerable area, with a thickness of 10,000 

 to 15,000 feet comparable with the rocks of the 

 same age in Nevada. The materials are largely 

 volcanic, diabase porphyrites becoming amyg. 

 daloidal; also agglomerates passing into diabase 

 tuffs. The sediments are marine limestones 

 and argillites. Certain limited areas are be- 

 lieved to be Lower Jurassic, though not sepa- 

 rated upon the map. 



Passing the Cretaceous development, the 

 Oligocene Tertiary, or Coldwater group, is quite 

 important, its materials consisting of aqueous 

 deposits, conglomerates, sandstones and shales, 

 in some places holding coal and lignite. None 

 of the beds are marine, and all are said to 

 be separated from the Miocene by uncon- 

 formity. 



Fully half the area of the map is occupied 

 by the Miocene, which is composed of volcanic 

 rocks over 9,000 feet in thickness. The lower 

 division consists mainly of augite-porphyrites ; 

 the middle of fine-grained tuffs that have been 

 laid down in water containing beds of lignite, 

 perhaps of merchantable value, and the upper of 

 basalts, melaphyres, etc., easily seen to have 

 been ejected from numerous local vents. Fossil 

 plants have been collected from all parts of the 

 Cretaceous and Tertiary series, and serve for 

 the basis of the stratigraphical reference and 

 assignment. 



The granites found in the Kamloops area are 

 of medium coarseness passing from biotite- 

 granite to hornblende-biotite granite, are some- 

 times foliated, especially near their contact 

 with Paleozoic strata, and are probably post- 

 Archean in age. 



Perhaps the most interesting part of the vol- 

 ume is the description of the geology of the 

 Montreal sheet by Dr. Ellis. This area lies be- 

 tween latitudes 45° and 46°, immediately north 

 of the international boundary and between 

 longitudes 72° and 7,4°. It is the first area 

 studied carefully by the Survey, as it embraced 

 the vicinity of Montreal, the chief city of the 



Dominion ; and it is interesting to United States 

 geologists because the formations pass from it 

 into our territory. It has also great historic 

 interest, as it has been the field of vigorous con- 

 troversy. 



Before 1860 it was supposed that its structure 

 furnished the key to the solution of the meta- 

 morphic problem of eastern America. Studies 

 by Sir William B. Logan furnished the founda- 

 tion for a peculiar paleontology, which referred 

 the terranes southeast from the St. Lawrence 

 to the horizon of the Chazy-Calciferous ; some of 

 these had, in the previous decade, been referred 

 to the Medina or Middle Silurian. Because of 

 the accurate stratigraphical and paleontological 

 studies of this area, it was claimed that the ex- 

 tension of the terranes southerly defined the 

 age of the crystallines of New England, all of 

 them being Silurian or Devonian. The Ver- 

 mont Geological Survey had accepted these 

 Canadian conclusions, fortified, as they were, 

 by the opinions of Professor James Hall. But 

 the Vermonters could not accept Logan's in- 

 tepretation of the structure of the Green Moun- 

 tains as they continued into Canada. Logan 

 called it the ' Danville and Sutton Synclinal ; ' 

 whereas on the southern side of the boundary 

 line no interpretation of the dips could justify 

 any such structure. In the midst of these per- 

 plexities of adjustment there came, at the end 

 of the year 1860, a communication from SirW. 

 B. Logan containing a letter from Barrande af- 

 firming the primordial (Potsdam) age of the 

 trilobites referred by Hall to the Hudson Eiver 

 group, and the consequent abandonment of a 

 belief in the Silurian age of the Olenellus slates. 

 Much readjustment of the details has been re- 

 quired, and it is only now, thirty-five years 

 after the publication of Barrande's letter, that 

 the details are properly presented. Instead of 

 the ' Danville and Sutton synclinal ' Dr. Ellis 

 gives us the 'Sutton mountain anticline,' and 

 there are broad expanses of pre-Cambrian and 

 Cambrian terranes to take the place of the for- 

 mer Middle and lower Silurian. This pre- 

 Cambrian Green Mountain area is about twenty 

 miles wide at the international boundary, 

 flanked on both sides by a Cambrian terrane and 

 there by the Cambro-Silurian. On the west side 

 the Calciferous sandrock seems to be absent be- 



