DRIFTS OF FLAilBOROUGH HEAD. 



409 



Boulders over 1 foot in 

 diameter. 



Origin. 



Carboniferous Limestone 

 (includiufij also a few 

 other Pahxjozoic Sedi- 

 mentary Rocks) 



Sandstones, Grit, Conglo- 

 merate, Sec. (probably 

 all, or nearly all, from 

 Carboniferous or other 

 Palaeozoic Rocks) 



Mesozoic Rocks (Jurassic 

 Limestones and Sand- 

 stones, Chalk, &c.) ... 



Basaltic and other Erup- 

 tive Rocks 



Granite, Schist, Gneiss, 

 &c 



Total 



<v 



W - (-» 



W S 1) 



y. v) ^ 



X ^ a. 



3-2 o 



O •-- r/J 



M-l ^ O 



i^ « ® 



o «i _; 



^ s 2 ; t;: 

 o 



per 

 cent. 



22-8 



£.5 



O 

 O 



<2 



>M Si 



= b -= ! ^ 2 = 5 



o 



G3 ^ 



per 

 cent. 



170 



14-4 45-0 



221 



37-3 



3-4 



220 



140 



2-0 



per 

 cent. 



23-3 



26-8 



10 

 43-2 



5-7 



bC-3 

 be o 



PQ-s 

 >< o 



per 

 cent. 



130 



150 



510 



19 



20 



1000 100-0 1000 1000 



6hs 



to' 





T3 \^ 



• ,M« 



" ■ 1 



"33 '-> 



>■ u 



tc y 1 



J 2 







3 -^ 



« *^ 



C- *^ 



^.S 





^ '" 



. - CD 



o ? 



" -n 



? S; 





S 33 



pq-a 





c'^ 













mnv, 

 bou 



rl ^ 



o 



."- o 



O r-H 



1—1 



j:j'M 



per 



per 



per 



cent. 



cent. 



cent. 



140 



130 



300 



250 



28-0 



180 



40-0 



480 



35-5 



18-0 



7-0 



15-5 



30 



100 



40 



10 



1000 



100-0 



As the boulders have, of course, been derived from various horizons, 

 the above table indicates only the relative proportion of the different 

 rocks contained in the whole mass of the drift without any discrimi- 

 nation of level. I believe that the rocks from the most distant 

 localities, such as the granites (other than Shap), schists, gneisses, 

 &c., are proportionately most plentiful in the Basement Clay ; while 

 boulders from the Carboniferous area of the north-west, though 

 everywhere predominant, are most strikingly so in the higher clays 

 and gravels. The researches of Mr. Alfred Harker have proved that 

 most of the basaltic rocks included in my lists have had their source 

 in the sills and dykes of tho Carboniferous, while the bulk of the 

 granitic and gneissic specimens "might have been derived either 

 from Scandiuavia or from the Scottish Highlands. Among them 

 are some undoubted Norwegian rocks, while none can be pointed out 

 as certainh/ brought from Scotland. It may well be, then, that the 

 whole of the doubtful rocks are also of Xorwegiau origin" *. 



Mr. Harker summarizes tho result of his examination of my Flam- 

 borough-Head specimens as under : — 



'' i. Among the boulders examined are some certainly from the 



south and west of Norway. 



* Alfred Harker. 'Petrological Notes,' Proc. Yorks. Geol. & Polvtechn. See. 

 vol. xi. (1890) pp. 300-307, and Ibid. pp. 409-423. 



Q.J.G.S. No. 187. 



L' F 



