448 Iloracc B. Woodward — Notes on the Devonian Rocks. 
tliem to produce sketch-maps, and in most cases to grasp tlie main 
geological featnres of the country when tliey could not attempt to 
follow out all the local points of structure ; and when we remember 
that they liad to Start as it were in a terra incognita, we may well 
speak with admiration of the grand work that was achieved in field- 
geology in the early part of this Century. 
While the greater portion of England and Wales has now beeil 
worked out in considerable detail, and its rocky structure repre- 
sented upon the Geological Survey maps, our knowledge of the 
Palseozoic country ofWest Somerset, Devon, and Cornwall, is almost 
entirely confined to sketck-maps, skowing the general grouping 
of the strata ; the determination and correlation of minor sub- 
divisions in the rocks, and the tracing out of their exact boundary- 
lines, having been as yet attempted only in a few localities. 
Thus the geological picture sketched partly by Sedgwick and 
Murchison and Godwin-Austen, remains for the most part very 
much as it was when left by the master-hand of De la Beche. And 
here it is only right to observe that the maps of this district, which 
were those first published by the Geological Survey, were the work 
of De la Beche as an amateur, assisted only by the voluntary contri- 
butions of other private workers. Consequently the same attention 
to minute accuracy with which he subsequently directed the labours 
of bis staff, could not possibly have been given to this early work, 
which covered an extent of ground that no one man could have 
thoroughly investigated in a lifetime. 
Another grand version has, however, been given to the geological 
outline of this district, and by a mau wliose experience put him at 
least on a par with any of his predecessors. A considerable modifi- 
cation in the Classification of the rocks, as maintained by the majority 
of those who had previously studied the country, was proposed in 
1863 and subsequent years by Jukes. And his observations, based 
to a large extent upon an intimate knowledge of the Carboniferous 
rocks and Old Red Sandstone in the south of Ireland, coupled with 
some previous acquaintance with the district, and with the advantage 
of the labours of those who had gone before him, gave to his 
opinions and conclusions a force which belonged to no other writer 
upon the subject. He attempted no more than others had done, but 
he drew a different outline, and instead of regarding the whole of 
the Devonian rocks as equivalent in time to the Old Red Sandstone, 
he maintained that only the lower divisions of the group could be 
classed with this formation, the slates and limestones representing 
the lower portions of the Carboniferous System. 
It is needless to enter here intö all the labyrinths of this con- 
troversy, as the subject has been elsewhere reviewed on several 
occasions during the past few years. 1 It is scarcely to be expected 
that a Settlement of the quest.ion can he gained until the whole of 
the country has been thoroughly worked out, and the accumulated 
observations of many observers have been carefully arranged and 
digested. It may not, however, be altogether fruitless if, while 
1 Quart. Journ. Science, Jan. 1873; Trans. Plymouth Inst., vol. v. p. 450. 
