340 lamplugh: the larger boulders of flambro' head. 
my survey, — no doubt by this time others are to be seen, and some 
of those I examined are buried under shingle - and measured and 
catalogued those which had any dimension exceeding twelve inches. 
In this way I compiled a list of 76 erratics, ranging in size from 
about one cubic foot to over thirty feet. Though probably all 
derived from the drift-beds of the cliffs immediately adjoining, where 
the sections consist chiefly of the Purple boulder clay and inter- 
stratified gravels, the smaller of these blocks are laid upon a shifting 
beach, and are thus liable to constant change of size and position, 
so that it will scarcely be necessary to particularize them ; but the 
larger masses have stood without perceptible change of position for 
several years to my knowledge, and these I shall describe, so as to 
guide anyone interested in the subject who may liave occasion at 
some future time to examine them. 
On analysis I find that my list contains — 
Per cent. 
28 Sandstones and Grits, undoubtedly of Carbonifer- ) _ ^^.^ 
ous age ... ... ... ... 3 
6 Limestones, undoubtedly of Carboniferous age .. . = 7 "9 
25 Sandstones, origin uncertain, but suspected to be 
Carboniferous 
3 Limestones, origin uncertain, but either IMag-l ^ ^.^ 
nesian or Carboniferous ... ... ... ) 
9 Basalts = 12 0 
4 Gneissic and Schistose Rocks ... = 5*3 
1 Granite (?) = 1*3 
76 lOO'O 
My knowledge of igneous rocks is unfortunately very imperfect, 
so that my descriptions of erratics of this class may not be very 
accurate, but the sandstones and limestones which I have put down 
as Carboniferous I have recognized either by their contained fossils 
or by some other well-marked peculiarity. My reason for suspecting 
that most, if not all, of the 25 dubious sandstones are also Car- 
boniferous is because I have not found among the blocks any 
recognizably Oolitic sandstone (from which formation it might be 
supposed from their appearance that some of the rocks had come), 
though fossiliferous beds and beds with marked peculiarities are so 
= 32-8 
