REVIEWS 77 
Memours of the Geological Survey of the United Kingdom. The 
Silurian Rocks of Britain. Vol. I, Scotland, 1899. By B. 
N. Peacu, JoHN Horne, and J. J. H. TEav. 
This publication, which comprises the first volume of a proposed 
monograph on the Silurian rocks of Great Britain and Ireland, treats 
of the Silurian formations of Scotland in a praiseworthy degree of 
completeness. It is a work destined to maintain the high standard of 
excellence attained by the British Survey Reports. 
The opening chapter is devoted to the physical features of the 
Silurian region. The region in general comprises the Southern 
Uplands which, lying between the Central Lowlands on the north and 
the Cheviot Hills and Solway Firth on the south, stretch from the 
North Sea to the Irish Channel. The topography of the region varies 
from the uniformly smooth or undulating types in the central and 
eastern parts to the rugged craggy type of the southwestern part. 
The Uplands vary in height from one to two thousand feet. The 
northern border is traversed by an extensive fault which lets down the 
Devonian and Carboniferous rocks of the north to form the surface of 
the Central Lowlands. 
The succeeding chapter is devoted to the history of previous 
researches among the rocks of this district. These researches cover a 
period of more than a century, and have engaged the attention of 
many of Britain’s foremost geologists of the past and present. Begin- 
ning with Hutton among others are the names of Hall, Fairplay, Nicol, 
Harkness, Murchison, Sedgwick, Ramsay, A. Geikie, J. Geikie, and 
Lapworth, besides the names of the authors, Peach, Horne, and Teall. 
To Lapworth is given the credit of establishing by paleontological and 
stratigraphical achievements the true order of succession of the Silurian 
strata. His studies of the sequence of the Silurian graptolite faunas 
made possible the correction of erroneous estimates of the thickness of 
the beds and enabled the structure of the region to be worked out in 
the most complicated areas. 
The stratigraphy and the tectonic arrangement of the rocks are set 
forth in the third chapter of the volume. ‘The Lower Silurian series 
is divided into the Arenig, the Llandeilo, and the Carodoc formations. 
The Arenig strata consist of cherts, mudstones, shales, and volcanic 
tuffs interbedded in places with tuffs, lavas, and agglomerates, asso- 
ciated with intrusive masses comprising serpentine, olivine, enstatite 
