Reviews— Winchell & Schuchert—L. Silurian Brachiopoda. 421 
waters of the Pleistocene lake, caused by the damming up of the 
eastern end of the Vale of Pickering at Filey, which is still blocked 
by glacial deposits. Undoubtedly the Vale of Pickering held 
a lake, but if a 200 feet gorge has been cut through the entire 
breadth of the Howardians within the period claimed, even allowing 
for a pre-existing stream flowing towards the Vale, we must again 
acknowledge the immense amount of erosion which has been effected 
in Pleistocene times. 
Attention is also drawn to this subject in reference to Cleveland, 
where the Jurassic rocks are encumbered by glacial deposits to a 
greater extent than elsewhere in Hast Yorkshire. One of the most 
characteristic features of this district is the number of rock gorges 
through which the existing streams flow, and which are due to the 
blocking of pre-glacial valleys by drift. Important inferences are 
drawn from the distribution of this drift throughout the Jurassic 
area. It is seen to cover a great part of the country north of the 
Esk, and in this region attains to considerable elevations. But neither 
over the high Moorlands south of that valley, nor throughout the 
Tabular Hills, has any been found, until we come to the local Drift 
of the lower slopes, which border the Vale of Pickering. From 
these facts he infers that the ice of the North Sea, impinging upon 
the coast of Cleveland, pushed its way nearly to the axis of the 
Jurassic highlands, and then divided into two streams, the westerly 
one moving down the Vale of York, whilst that to the east inclined 
to follow the coast-line. Clearly Mr. Strangways is not afraid of the 
“ Glacial Nightmare.” 
Two chapters on Economic Geology conclude the first volume. 
The second volume is devoted to a most elaborate series of tables 
of fossils, prefaced by a very complete bibliography. The author 
observes that this catalogue was originally compiled, on a smaller 
scale, to facilitate the work of the Geological Survey, but that, 
having been found very useful in that connection, he considered its 
publication might be of some utility to students of this district. 
In this view we cordially agree, and we heartily congratulate Mr. 
Strangways on the completion of the entire Monograph. 
II.—Tue Lower Sinurran Bracuropops or Minnesota. By N. H. 
WINCHELL AND CHaArRLes ScuucuErRT. Extracted from Vol. III. 
of the Final Report of the Minnesota Geological Survey. 
Chapter V., Plates XXIX. to XXXIV., June 6th, 1893. 
HE authors of this Monograph, expert, industrious brachio- 
podists, collected the materials for their researches on the 
Lower Silurian Brachiopoda of Minnesota from the Upper third 
of the Trenton Limestone in the vicinity of Minneapolis and the 
Trenton shales near St. Paul’s and Minneapolis. They adopt the 
names brachial=ventral, and pedicle=dorsal valves, and give clear 
and useful definitions of other terms employed. MHyatt’s nomen- 
clature is used for ontogenetical inquiries, for which, in some instances, 
abundant material was forthcoming. ‘The classification agrees with 
that recently proposed by Schuchert, embodying Beecher’s orders. 
