Reviews — Stratigra'phy of North America. 171 



other familiar names, those of Bedford Oolitic Limestone, Mansfield 

 Sandstone, and Elgin Sandstone applied to Carboniferous strata in 

 the United States. Nevertheless, where such formations are of 

 minor or purely local interest the matter is not very serious. In 

 the work before us perhaps the majority of local geological divisions 

 have a distinctly American savour ; such as the Cusseta Sand, the 

 Cussewago Sandstone, Swearinger Slates, Sacramento formation, 

 Perry Sandstone, Sillery formation. Great Smoky Conglomerate, and 

 Birdseye Limestone, to say nothing of other and more familiar names 

 derived appropriately from native American localities. 



Turning now to the geological map, we find it to comprise four 

 large sheets, on the scale of 1 : 5,000,000 or about 1 inch to 80 miles. 

 It includes the north-western corner of South America and extends 

 therefrom to the Bering Strait, the Parry Islands, and Greenland, 

 Avith insets showing the Windward and the Aleutian Islands. Each 

 map has its separate series of index-tablets, desirable because in some 

 areas the systems have been mapped in more detail than in others 

 where they are undifferentiated. Moreover, there are some differences 

 in the classifications adopted by the Surveys of Canada, Mexico, and 

 the United States, while the chronological limits of formations 

 naturally vary. Printed on one sheet of the map there is a general 

 series of colour tablets, which shows at a glance the scheme of 

 classification, the larger groupings being Archeozoic, Proterozoic, 

 Paleozoic, Mesozoic, and Cenozoic, together with Pre-Cambrian and 

 Post-Cambrian Intrusive rocks, and Tertiary and later Effusive rocks. 

 It should be remembered that Professor Lap worth used the term 

 Proterozoic or Protozoic for Cambrian, Ordovician, and Silurian. In 

 the work before us Proterozoic is applied to the Pre-Cambrian, or in 

 other words to Algonkian, which includes Huronian and Keweenawan. 

 It is eminently satisfactory to find the names for the geological 

 systems in harmony with those in general use in Europe, such as 

 Cambrian, Ordovician, Silurian, etc. 



-The immense advance in knowledge of the geology of North 

 America during the past sixty or seventy years is manifest when we 

 compare this new map with the area coloured in Ly ell's " Geological 

 Map of the United States, Canada, etc., compiled from the State 

 Surveys of the United States and other sources ", and published by 

 John Murray in 1845. Very little of Canada and but a small region 

 west of the Mississippi were then coloured geologically. The present 

 map has been compiled in co-operation with the Geological Survey of 

 Canada and the Geological Institute of Mexico, under the supervision 

 of Mr. Willis and Mr. George W. Stose. 



Intended for use as a wall-map, as well as for local reference, the 

 colours have been carefully selected, and the guiding principles in 

 their adoption are set forth in an interesting and instructive manner. 

 The International scheme of colours was found unsuitable ; in North 

 America, for instance, few distinctive tablets are required for the 

 Mesozoic divisions as compared with those of the newer and older 

 formations.' The main systems are depicted, sometimes locally 

 divided as in the case of the Carboniferous into Mississippian and 

 Pennsylvanian, sometimes united as in the cases of Eocene and 



