BR REVIEWS 
Ancient volcanoes, the nature of the material erupted, and the several 
types of volcanoes. Underground phases of volcanic action are also 
described ; and the effects of subsequent denudation in exposing the 
rocks and their influence on the topography and scenery are discussed. 
The major part of the work treats in detail of the volcanic phenom- 
ena connected with each period of activity, beginning with that in the 
pre-Cambfian time. Upon petrographical grounds the most ancient 
Lewisian gneiss, corresponding to what is often called Archean, is 
considered to have been originally a mass of various eruptive rocks. 
Although they have been subjected to great mechanical deform- 
ation, the present banded structures are connected with the original 
igneous condition of the rocks. They were probably underground 
lavas, possibly connected with extrusive bodies. With these rocks are 
associated dikes of basic and acid rocks. Rocks of volcanic origin 
undoubtedly occur in the Dalradian schists of Scotland and in the 
gneisses and schists of Anglesey. The Uriconian, Malvern, and Charn- 
wood Forest volcanic rocks are all of pre-Cambrian age. The volcanoes 
of Cambrian time occurred in South Wales, North Wales, Malvern Hills, 
and Warwickshire; those of Silurian time occurred in Wales, North of 
England and in Scotland, and Ireland ; partly in the Lower, partly in 
the Upper Silurian. Volcanic activity was pronounced in Middle 
Devonian times but in certain districts extended into the Upper Devo- 
nian. Inthe period of the Old Red Sandstone there existed numer- 
ous centers of volcanic activity. In Lower Old Red Sandstone time 
they extended from Shetland to the Chevoit Hills in England and even 
to Lake Killarney, and from the coast of Berwickshire on the North 
Sea to near Lough Erne in the north of Ireland. They are less numer- 
ous in Upper Old Red Sandstone time, occurring in the southwest of 
Ireland and the north of Scotland. The Carboniferous age was 
marked by prolonged volcanic activity in Scotland and by restricted 
activity in England and Ireland. ‘The volcanoes were partly of the 
plateau, partly of the puy type, accompanied, of course, by intrusive 
bodies. The Permian volcanoes of Scotland and England are much 
less important. 
Four fifths of the second volume are devoted to the volcanoes of 
Tertiary time, for the reason that they are the most recent and their 
rocks are the freshest and most abundant. They occur along the west 
coast of Scotland and the northeast of Ireland. ‘The dikes, plateau, and 
fragmental rocks are described in detail, and an account of the mod- 
