PREFACE. xxi 
were correct. I did not, however, mean to let the matter rest, but to re-examine the whole 
Paleozoic question as soon after the publication of the Silurian System as I could find a 
long vacation at my command. 
After I had parted with my friend near Bala in 1834, I thought the rest of the summer 
well employed in making traverses through the true Silurian rocks of Denbighshire, and in 
partially exploring the Carboniferous rocks of Denbighshire and Flintshire. In 1835 I spent 
some time in exploring the North of Ireland, after the breaking-up of the British Association 
at Dublin. It had been confidently asserted during the Meeting, that our Geological theories 
were put to open shame by the Culm-Measures of North Devon, which (though containing 
beds of coal and many true Carboniferous fossil plants) were in fact interpolated among the 
oldest Slate rocks; and that the Geological Society were discredited in not having given a 
proper prominence to this notorious fact. 
In these expressions of vituperation, a challenge seemed directed personally to Murchi- 
son and myself, which we accepted with perfect goodwill. Accordingly, we visited the 
Northern Coast of North Devon next year, and resolved, if possible, to determine what was 
the true position of the Culm-Measures. We had no difficulty in making out the Natural 
groups of Strata, which presented themselves in a traverse from the extreme Northern Coast 
to the dark coloured limestone, which ranges a little South of Barnstaple, and crosses a great 
part of the County in a direction nearly East and West. Our attempt was at length quite 
successful. The Culm-Measures were proved to be the highest rocks of North Devon, 
and though anomalous in many of their mineralogical details, they were by no means 
anomalous in their position; for the calcareous bands which appeared along their northern 
and their southern base, were but one of the forms of the Carboniferous limestone. 
But what were the groups of Slate rocks, which rose from beneath the Culm-Measures, 
and were exhibited in various undulations, ranging nearly East and West between the parallel 
of Barnstaple and the northern shores of Devon? The fossils in these groups exhibited 
some forms that were then unknown to us. But the highest group of all, which we will call 
the Barnstaple group, was eminently fossiliferous, and was pronounced by Murchison to 
belong to the Caradoc sandstone. We collected from this group a good series of organic 
remains, and sent them to Mr Sowerby; and not long afterwards my fellow-labourer received a 
dispatch from Mr Sowerby, which informed him that he had made a correct determination 
of the age of the Barnstaple fossils. 
I was little satisfied with this determination, which virtually cost me the work of two 
Long Vacations in the years 1837 and 1838. In 1837 I was joined for a short time in South 
Devon by my friend Mr Godwin-Austen, and we did not quite complete any part of our 
survey, both being unexpectedly called away. But during a long Summer of 1838 I worked 
