TRANSACTIONS OF SECTION C. 767 
the geologists of other countries, to whom the necessity for this kind of study is 
apparent, and who are carrying it on with great success. , 
_ The value of detailed work on the part of the stratigraphical geologist is best 
grasped if we consider the recent advance that has been made in our science owing 
to the more or less exhaustive survey of the strata of various areas, and the appli- 
cation of the results obtained to the elucidation of earth’s history. A review of 
this nature will enable us not only to see what has been done, but also to detect 
lines of inquiry which it will be useful to pursue in the future; but it is obvious 
that the subject is so wide that little more can be attempted than to touch lightly 
upon some of the more prominent questions. A work might well be written 
treating of the matters which I propose to notice. We have all read our ‘ Prin- 
ciples of Geology,’ or ‘The Modern Changes of the Earth and its Inhabitants 
considered as illustrative of Geology,’ to quote the alternative title; some day we 
may have a book written about the ancient changes of the earth and its inhabitants 
considered as illustrative of geography. 
Commencing with a glance at the light thrown on inorganic changes by a 
detailed examination of the strata, | may briefly allude to advances which have 
recently been made in the study of denudation. The minor faults, which can only 
be detected when the small subdivisions of rock-groups are followed out carefully 
on the ground, have been shown to be of great importance in defining the direction 
in which the agents of denudation have operated, as demonstrated by Professor 
W. C. Broégger, for instance, in the case of the Christiania Fjord ;' and I have 
recently endeavoured to prove that certain valleys in the English Lake District 
have been determined by shattered belts of country, the existence of which is 
shown by following thin bands of strata along their outcrop. The importance of 
the study of the strata in connection with the genesis and subsequent changes of 
river-systems is admirably brought out in Professor W. M. Davis’s paper on ‘The 
Development of certain English Rivers,” a paper which should be read by all 
physical geologists; it is, indeed, a starting-point for kindred work which remains 
especially for local observers to accomplish. Study of this kind not only adds to 
our knowledge of the work of geological agencies, but helps to diminish the im- 
perfection of the record, for the nature of river-systems, when rightly understood, 
enables us to detect the former presence of deposits over areas from which they 
have long since been removed by denudation. 
An intimate acquaintance with the lithological characters of the strata of a 
district affords valuable information in connection with the subject of glacial 
denudation, The direction of glacial transport over the British Isles has been 
largely inferred from a study of the distribution of boulders of igneous rock, whilst 
those of sedimentary rock have been less carefully observed. The importance of 
the latter is well shown by the work which has been done in Northern Europe in 
tracing the Scandinavian boulders to their sources, a task which could not have 
been performed successfully if the Scandinavian strata had not been studied in 
eat detail. I shall presently have more to say with regard to work connected 
with the lithological characters of the sediments. Whilst mentioning glacial 
denudation, let me allude to a piece of work which should be done in great detail, 
though it is not, strictly speaking, connected with stratigraphy, namely, the 
mapping of the rocks around asserted ‘rock-basins.’ I can find no actual proof 
of the occurrence of such basins in Britain, and it is very desirable that the solid 
rocks and the drift should he carefully inserted on large-scale maps, not only all 
‘around the shores of several Jakes, but also between the lakes and tbe sea, in order 
to ascertain whether the lakes are really held in rock-basins, Until this work 
1 W. C. Brogger, Nyt. Mag. for Naturvidensk, vol. xxx. 1886, p. 79. 
2 W. M. Davis, Geograph. Journ., vol. vy. 1895, p. 127. 
5 It is desirable that the boulders of sedimentary rock imbedded in the drifts of 
East Anglia should be carefully examined and fossils collected from them. The 
calcareous strata associated with the Alum Shales of Scandinavia and the strata of 
au Saher mt emp y ee of that region may be expected to be represented amongst 
e boulders, 
