206 
NATURE 
aa ty 
| [NOVEMBER 16, 1916 
boniferous limestone in a large part of the neigh- 
bourhood of Cleator and find immense bodies of 
ore to reward him.” 
It is claimed for the Cleator Linen Thread Mill 
(now included in the great Thread Combine) that 
it is “the oldest flax-spinning mill in the country, 
and perhaps in the world.” Winding thread on 
spools was first started here, the thread having 
previously been done up in hanks. It is strange, 
therefore, that Mr. Caine, in a dissertation upon 
place-names, should seek to connect that of a 
field close to the mill, Linethwaite, with the 
Anglo-Saxon “‘linde,” a lime tree. It is plain 
Norse for “‘flax-field ”—lin-thveit. A list of the 
flora and fauna of Cleator is given in an appendix, 
but it is valueless for any scientific purpose, inas- 
much as none but English popular names are 
given. It does not carry one very far to be told 
that in this parish are found the linnet, the goose, 
the orchis, the gentian, etc., with no indication of 
species. 
A COMPOSITE AMERICAN TEXT-BOOK OF 
GEOLOGY, 
A Text-book of Geology. By Prof. L. V. Pirsson 
and Prof. C. Schuchert. Part i., 
Geology. By Prof. L. V. Pirsson. Pp. vii+ 
444. Price 10s. net. Part ii., Historical 
Geology. By Prof. C. Schuchert. Pp. yi+ 
405-1026. Price 12s. net. (New York: J. 
Wiley and Sons, Inc.; London: Chapman and 
Hall, Ltd., 1915.) 
(5, BOEOEY, being such a many-sided science, is 
especially handicapped in regard to text- 
books. It is provided .with a library of books 
dealing with its various subdivisions and aspects, 
but the provision of an up-to-date manual which 
deals with the whole range of the subject in about 
a thousand pages, and of the standard required 
by students in higher technical schools and by 
those taking geology as a secondary subject in 
universities, is a perennial difficulty. Specialisa- 
tion in geology has gone so far that it is becoming 
impossible for any one author to deal with the 
whole science in the detail required in such a work. 
The new text-book of geology by Profs. Pirsson 
and Schuchert, with chapters by Profs. Barrell 
and Lull and Dr. Ulrich, show the effort to over- 
come this difficulty by joint authorship. That 
method has its own drawbacks, for it is very diffi- 
cult thus to secure that unity of view and uni- 
formity of standard which are indispensable in 
an educational text-book. 
The first part of this work, by Prof. Pirsson, 
deals with physical geology. It is divided into 
two divisions, dynamical and structural, and in 
the course of 400 pages gives a most excellent 
summary of these subjects. Its illustrations are 
numerous and clear, and are all useful. Those 
illustrating the geological conditions of arid re- 
gions are especially good. His account of the 
igneous rocks is short and conservative, and 
British teachers may be grateful for the fact that 
NO. 2455, VOL. 98] 
Physical , 
he does not mention the American classification or 
adopt its terminology. A few relatively unim- 
portant slips occur, such, for example, as the 
remark on p. 178 that the one boring in a coral 
atoll in the Pacific shows a thin cap of coral “on 
the volcanic rock which forms the main mass.” 
The author attributes (p. 79) the fact that the 
Caspian is fresher than ordinary seas to the pre- 
cipitation of its’ salt in Karabugas; but it would 
appear more probably due to the former dilution 
of the Caspian by the Volga. Prof. Pirsson intro- 
duces into geology the term “ nonconformity ” for 
those varieties of unconformity in. which.the dip 
of the formations is visibly different; for the other 
section of unconformities he ‘accepts: Grabau’s 
term of disconformity. His description of pot- 
holes as a minor feature would appear to under- 
rate their significance, for their formation is prob- 
ably the main process by which mountain streams 
deepen their valleys in hard rock. 
The chapter on the formation of mountains is 
one of the most interesting in the volume. In 
spite of some American opinions to the con- 
trary, the author concludes that the crust is 
contracting in consequence of the lessened volume 
of the earth as a whole; and he is disposed 
to attribute the shrinkage, not to cooling, but 
to chemical changes in the internal material. 
He adopts also the steadily growing view that 
crustal movements occur with a rhythmic 
periodic progression; but the author will sur- 
prise many of his readers by his conclusion that 
the earth, “except locally or to a superficial 
depth, may not be hot, at least in any such sense 
that it could experience the notable contraction 
from loss of heat demanded for the origin of the 
folded ranges’’ (p. 366). The author refers to 
recent suggestions throwing doubt on the origin of 
the West American block mountains by faulting; 
but he concludes that the dominant processes in 
the formation of many, if not most, of these 
ranges are the faulting of the region and the 
tilting of the blocks. In his classification of 
mountains it is perhaps a pity that the author has 
not adopted the usual sequence of terms. He 
reverses the order of chain and system, and re- 
presents several mountain systems as forming a 
mountain chain; and he continues that a com- 
bination of mountain chains constitutes a cordil- 
lera. The term ‘“‘cordillera ”’ seems best restricted 
to a mountain system such as the Andes, com- 
posed of parallel chains. ¢ 
Prof. Schuchert’s part of the work, which is 
also published as a separate volume, consists of 
a most interesting series of essays. But it would 
appear of less use to British students as a college 
text-book than the first part. It is overweighted 
at the start by the long hypothetical pre-geological 
history of the earth. The arrangement of the 
material, and such illustrations as the portraits 
of geologists, are less suitable for the technical 
student than for the general reader; thus most 
students would probably have found it more con- 
venient to have the descriptive paleontology all 
