Geology and Mineralogy. 77 



the Devonian of England and Wales ; the Carboniferous, and the 

 Permian. After the Permian period, no volcanic or igneous 

 eruptions occurred again until the Tertiary. 



In the author's summary of the remarkable facts he has pre- 

 sented, the following are some of the conclusions stated. The 

 belts, of volcanic activity are ranged nearly north and south, 

 along the length of the British Isles from the south of Devon- 

 shire to the Shetlands ; but no trace of them occurs through 

 eastern England, from Berwick to Exeter, if we except the dikes 

 in the northern counties. Moreover, the Central Highlands of 

 Scotland were exempt through all the time. 



In this western tract, volcanic activity was almost continuous 

 from the Archaean to the close of the Paleozoic; and reappeared 

 in the Tertiary. The absence from the Mesozoic accords with 

 the general quiet over the European continent. 



The sites of the eruptions were not determined by lines of 

 faults; but there is this remarkable fact that they were confined 

 to the low grounds and valleys, such as the great depression 

 between the Highland Mountains and the Southern Uplands, 

 which was the chief center of volcanic activity in Scotland during 

 the later half of the Paleozoic. Again in the Tertiary, the great 

 outpouring took place in the long depression between the Outer 

 Hebrides and the mainland of Scotland. The volcanic action 

 occurred on sinking rather than rising areas, that is, on areas 

 where a great thickness of sediments were formed. There was a 

 gradual diminution in the extent of the eruptions from the Silu- 

 rian to the Permian, when there were only small scattered vents. 

 In the earlier Paleozoic lava-eruptions were most abundant, while 

 in the later in very many cases there were only ejections of ashes, 

 making tufa-cones. 



In each eruptive period the Tertiary included, there was a 

 change sooner or later from basic to acidic lavas. When a second 

 period commenced in the same region there was usually again the 

 same succession — a beginning with basic and an ending with 

 acidic. The eruptions of the Northwest Highlands were solely 

 fissure eruptions ; and the same kind prevailed in the Tertiary. 

 At other periods the eruptions were connected with true volcanic 

 vents. A great crater-like cavity was sometimes left, that became 

 filled with the following rock-deposits. 



2. New Jersey Geological Report for J 891, John C. Smock, 

 State Geologist. 270 pp. 8vo. Trenton, N. J., 1892. — This volume 

 contains an extended account of the drift formations of New 

 Jersey by Prof. R. D. Salisbury, illustrated by several photo- 

 types of the region of the terminal moraine and of other bowlder 

 scenes, and also by many wood-cuts, and a map. The paper is an 

 important contribution to the general subject of glacial phe- 

 nomena. 



Mr. Lewis Woolman reports on the horizons of Artesian wells 

 in Southern New Jersey and other parts of the Atlantic border. 

 He mentions the occurrence of one or two upper horizons de- 



