THE GEOLOGY OF PLYMOUTH. 
451 
geological science was hardly recognised in the West of England, 
except by a few scattered observers. Alike in the date and 
character of his researches, Mr. Hennah is entitled to be regarded 
as the father of our local geology. 
And there is another local investigator of geological phenomena, 
a third member of this Institution, to whose writings I am likewise 
bound to refer. Mr. J. C. Bellamy, in his " Natural History of 
South Devon, " published in 1839, recorded a number of important 
facts connected with the geology of this neighbourhood, very 
different in value to the crude generalizations and hasty theories 
which, misled by the imperfect knowledge of the time, he put forth. 
If by the aid of the wider investigation, systematized conclu- 
sions, and clearer acquaintance with the workings of Nature, of 
the present day, I am enabled now to present a fuller and more 
accurate view of the history and conditions of the geology of 
Plymouth and its neighbourhood, I desire at the outset to express 
my sense of the value of the labours of those who have gone before, 
and of the honour they conferred upon this Institution. And if I 
do not mention the names of others associated with us who have 
done good work in this direction, it is partly because happily they 
are yet upon our muster roll, partly because I shall have special 
cause to express my obligations to them as my work proceeds. 
It is my desire to bring the results of the labours of other inves- 
tigators, with my own, into one connected whole, and to give as 
complete an account as is here possible of the conditions of our 
local geology, viewed in the light of modern science. 
Devonian Rocks. 
Geologists long hesitated in opinion concerning the exact place 
of the older rocks of Devon in the geological scale — the relative 
chronological position which they occupy. When stratigraphical 
geology was in its infancy, the rocks of this locality were frequently 
assigned a higher antiquity than that which any one would now 
allow. Playfair, in 1802, said that there were no rocks of a more 
distinctly primary appearance than those around Plymouth ; and 
thence opinion veered to the view that they were what in those 
days was called Transition. Sir Henry de la Beche, in his earlier 
publications, with certain of his predecessors, classed them under 
one of the most general and indefinite of geological terms — based 
chiefly on lithological likeness to certain rocks in Germany, so 
