492 Percy F. Kendall — Glacial Geolocjy. 



and for answers, a disproportion intensified when the questioner 

 possesses the ability of Mr, Eeade, I will address myself to two 

 points, and, having stated the facts so far as I can ascertain them by 

 personal observation and by reading all the literature available to 

 me, I will offer a few words by way of contrasting the different 

 theories advanced to account for the phenomena. I purpose dealing, 

 firstly, with the distribution of erratics in Lancashire, Cheshire, and 

 the adjacent counties, and secondly, with the nature and distribution 

 of molluscan remains found in the Anglo- Welsh. Drift. 



I. The Distribution of Erratics. 



The erratics of the region I have selected are divisible into two 

 tolerably well-defined groups — 



a. Stones of foreign origin. 



b. Stones of demonstrably local origin. 



The former category includes the Granitic Rocks, Lavas, and 

 ashes of the Western side of the Lake District, with a few stragglers 

 from the Eastern side, such as the odd boulder of Shap granite found 

 by Mr. Eeade on Moel Tryfaen, and the sparse trail of blocks of the 

 same rock traced by Mackintosh, Tiddeman, De Ranee, and others, 

 from the angle of Morecambe Bay in a curved line round via 

 Longridge to Whalley. It also includes numerous examples of the 

 granites, grits, and other well-marked types of rock found in Gallo- 

 way and the neighbourhood of Criffel, Some half-dozen pebbles 

 have also been recorded by Mr. Lomas of the remarkable Eurite of 

 Ailsa Craig.^ Flints also occur co-extensively with the other foi'eign 

 rocks, and it has been assumed that they are necessarily of Irish 

 origin, but from the fact that they are almost invariably of small 

 size and much waterworn, I long ago infei'red that they were 

 immediately derived from some bed of river-gravel which had lain 

 in the path of the ice which brought them into Lancashire. Whether 

 their more remote origin was in Antrim, in the submarine extension 

 of the Antrim Chalk, or in some other submerged outcrop of chalk, 

 such as that which Mr. Goodchild supposes to exist at the mouth of 

 the Solway Frith, matters not at all. If they come from a river- 

 gravel the precise spot whence they were derived is immaterial. 



With this enumeration the list of foreign rocks is completed. It 

 is true that Dr. Hatch ^ thinks he has recognized Dolerites from 

 Mull! but he gives no special locality in Mull, and from an exten- 

 sive experience of Mull rocks I have no hesitation in saying that it 

 is utterly futile to attempt a generic diagnosis. 



Petrographers should remember the Anglesea Picrite and beware 

 of confident identification of basic or ultrabasic Igneous rocks. 



Near the mouth of the Vale of Llangollen, and thence south east- 

 ward, Welsh rocks make their appearance, and of these and of their 

 peculiar distribution due account must be taken. 



This mere cataloguing gives no idea of the grouping of the boulders, 

 a subject which has apparently received less of Mr. Reade's attention 



1 Brit. Assoc. Report, 1892. See also Proc. Manch. Lit. & Phil. Soc. Feb. 1891. 

 * Brit. Assoc. Report, 1890, and Morton's Geol. of Liverpool, 2nd edition. 



