PREFACE. =_— 
North of Builth, and to ascertain their relation to the chain of Mynedd-Epynt; and especially 
to ascertain whether the Llandeilo Flags were to be placed above or below the conglomerates 
of Dol-Fan, which ran into a remarkable chain, now I believe regarded as upper Llandovery 
rocks. He was then a very youthful observer, and had not learned to trust himself, when 
the phenomena before him seemed to contradict the opinions of those whom he considered 
of high authority. He brought back to me, however, at the end of the summer, a very 
elaborate Report, from which after its perusal I could derive no definite result; and some 
years afterwards it was returned to its author, who confessed that it was erroneous, and I 
believe destroyed it. 
I spent the whole summer following (1845) in going over a part of my old work in 
Cumberland, Westmorland, and North Lancashire, endeavouring to bring the rocks above 
the Coniston Limestone (the equivalent of the Bala) into some accordance with the Groups 
of the Upper and true Silurian System. There could be no doubt that the Limestones 
of Bala and Coniston were of the same age. The fossils were numerous and almost identical 
in species. It was equally certain that the highest groups of the Westmorland Slate rocks, 
that overhang the Valley of the Lune near Kirkby Lonsdale, were on a parallel with the 
upper Ludlow rocks, as seen near the banks of the Towey: but how to bring the 
intervening groups into strict comparison with the successive upper Silurian Groups, was a 
task which I have never, to this day, performed to my entire satisfaction. 
I mention these facts in their order, with no motives I trust of personal vanity; but to 
prove with what steady perseverance I went on with the task that was before me. 
My object, from the first, had been to write a general work upon all the Paleozoic Rocks 
of England and Wales; and with this object still in view I went on from year to year, accumu- 
lating materials, which at length became too much for my sustaining powers. I had been 
much interrupted for many successive years by attacks of suppressed gout, and by very alarming 
attacks of congestion of the head; and at length the infirmities of old age had gathered 
round me before I had put my work in order. I will, however, leave this digression and 
come back to my Cambrian task. 
So far my present Preface has been associated with many happy and bright remem- 
brances—social and physical. 
What is about to follow will be less satisfactory to the reader; and will be associated 
in my memory with acts which very painfully affected me with involuntary distrust of some 
whom I had counted among my best and dearest friends, and threw a moral shade over 
all the latter years of my Geological life. 
It will perhaps be said that after the death of Sir Roderick Impey Murchison and 
Mr Warburton, it is wrong to revive the controversy I had with them, as I have already 
d 
