228 
Mr. Griffith has also demonstrated by sections the unconform- 
able position of the carboniferous and old red sandstone formations, 
which overlie older and more highly inclined slates in the counties 
of Kerry, Cork, Waterford, and Wexford. 
Mr. Charles William Hamilton has likewise adopted similar 
changes; and believes that the slates which occupy a large space 
between the Mourne Mountains and Dublin are equivalent to those 
near Cork, which he now transfers to the old red sandstone. 
Mr. Greenough, in the new edition of his map of England, repre- 
sents nearly the same boundaries and order of succession in Devon 
and Cornwall as we find in the maps of Mr. Dela Beche and Messrs. 
Sedgwick and Murchison ; but in his memoir connected with the 
map, adopting the name of Carbonaceous series for the culmife- 
rous rocks, he substitutes that of Upper killas for the Devonian 
system of Sedgwick and Murchison, (including under that term 
the old red sandstone of Herefordshire,) and Lower killas for the 
slates inferior to the Silurian system, which they have termed Cam- 
brian. 
Mr. Greenough, in his memoir, also shows by quotations from Dr. 
MacCulloch, that the undisputed old red sandstone of the north of 
Scotland exhibits, at intervals, the same great changes of mineral 
character, that occur in the strata intermediate between the Carbo- 
naceous and Silurian systems in the west of England and on the 
borders of Wales; and justly infers the inadequacy of any one term 
to characterize formations which vary so much in lithological com- 
position, that at one place they present the condition of a fine- 
grained silky slate, at another of sandstone, and at a third that of 
coarse gravel and conglomerate rock. 
Thus, with respect to the slate rocks of Devon, Cornwall and 
Wales, the difficulties are reduced to those of an unsettled nomen- 
clature ; whilst nearly all parties are in unison as to the fundamental 
fact of referring the slates of South Devon and Cornwall to the epoch 
of the old red sandstone formation. The term grauwacke, however, 
I rejoice to think, will not be condemned to the extirpation which 
has been threatened from the nomenclature of geology; it may still 
retain its place as a generic appellative, comprehending the entire 
transition series of the school of Freyberg, and divisible into three 
great subordinate formations:—the Devonian system of Sedgwick 
and Murchison being equivalent to the upper grauwacke, the Si- 
