398 LAMPLUGH : LARGER BOULDERS OF FLAiMBOROUGH HEAD. 
purposes of comparison, the percentages yielded by the eight hundred 
might be'safely accepted for the whole number. 
My own classification of the rocks, being based only on an 
examination in the field, is rough and unsatisfactory where the 
igneous blocks are concerned. But fortunately, through the kind 
co-operation of Mr. A. Harker, it has been possible to add a detailed 
statement of the petrological characters of a selection of the most 
interesting boulders, with suggestive notes af< to their probable origin. 
In most of these cases slices have been cut, and Mr. Harker has 
examined the specimens microscopically. The details of his work is 
printed separately at the end of this paper, and will, I think, be 
found the most exact and important contribution which has yet been 
made to the petrology of these erratics. 
The composition of the eight hundred boulders is shown in the 
following table, the system of classification being that adopted 
in my former papers : — 
Table 6. — 800 boulders on the shore between south sea 
landing and the extremity of flamborough head. 
Boulders. Per centum. 
189 Carboniferous Limestone ... ••■ = 23'6 
166 Sandstone and Grit, probably nearly all Carboni- 
ferous* ... ... ... ••• = 20*8 
4 Limestone, origin doubtful, probably Magnesian = O'o 
12 Pebbly Quartzite and conglomerate (Palaeozoic) | 
1 Coarse Breccia (Palaeozoic) ... . . V= r8 
1 Clay-slate (Palaeozoic) ... ... ) 
10 Liassic and nodular Limestone, (Secondary) = 1*3 
248 Fine-grained dark Basalt ... ... j 
81 Coarse-grained dark Basalt ... ... >= 437 
21 Grey doleritic Basalt ... ... ... ' 
22 Porph}Titic Felstone, &c. ... .... = 27 
30 Granite, Syenite, &c., (including 4 of Shap Granite)= 3*8 
15 Gneiss and Mica-schist ... ... = VS 
800 100*3 
* My reasons for Bupposing the majority of the doubtful Sandstones to be 
Carboniferous are stated in Part i., supra cit., p. 341. 
