EBRATIC BLOCKS OF ENGLAND AND WALES. 425 
34, Resuits of a Systematic Survey, in 1878, of the Drructions 
and Limits of Disprrston, Mopx of Occurrence, and ReLation 
to Drirr-peEpostts of the Krratic Buocxs or Boupers of the West 
of ENewanp and Kast of Waxes, including a Revision of many 
Years’ previous Osservations, By D. Macxintoss, Hsq., F.G.S. 
(Read March 26, 1879.) 
[Puare XXIT.] 
ConrENTSs. 
TI. Introductory Remarks and Definitions. 
Il. The great Kirkcudbrightshire Granite-dispersion. 
III. The great Cumberland Granite- and Felstone- dispersion. 
IV. South-easterly Hxtension of the great Arenig-Felstone-dispersion. 
VY. Chalk Flints and Lias Fossils associated with Northern Boulders. 
VI. Absence of striated Rock-surfaces over the Southern Part of the Boulder- 
strewn Area. 
VII. Remarks on local Boulder-dispersions. 
VIII. Positions of Boulders relatively to the matrix of Drift-deposits. 
IX. Explanation of Map. 
X. Tabular View of the Successive Stages of the great Glacial Submergence 
during which the Boulders of the west of Hngland and North Wales 
may have been transported. 
I. Inrropuctory RemMarKs AND DEFINITIONS. 
[THoven long familiar with the erratic blocks or(as they are now more 
generally called) boulders of the west of England, and though I had 
written many papers on the subject, which appeared in the ‘ Quart. 
Journ. Geol. Soc.’ and ‘ Geological Magazine,’ I lately saw the neces- 
sity for a systematic revision of what I had done, and more especially 
for an extension of my observations in a south and south-east direc- 
tion, where they could be made to throw some clear light on the 
nature and sequence of glacial events*. As no attempt has hitherto 
been made to treat the subject of erratics as a distinct branch of 
science, and as most readers might probably expect to find in a paper 
on the subject little more than an inventory of facts, it may be well 
to begin with a few remarks and definitions calculated to excite a 
scientific interest in the subsequent detailed statements. | 
1. Importance of Boulders as a Key to the Interpretation of Glacial 
Events—Relative Claims of Land-ice and Floating ice.—Notwith- 
standing that very few writers on the Glacial period have paid much 
attention to boulders (one distinguished glacialist told me that he 
purposely avoided them), I think it can be shown that in an area 
such as that extending from the south coast of Scotland to the west- 
midland counties, the positions and directions of dispersion of various 
kinds of boulders must be capable of throwing much light on the 
character and mode of action of the ice by which they were trans- 
ported. An illustration of this may be found in the truly wonderful 
concentration of granite blocks west and north of Wolverhampton, 
* Tn this undertaking I was aided by the Goyernment-Grant Committee. 
