Notices of Memoirs—E. Wethered—Lr. Carboniferous. 568 
however, the dolerite of Llanfawr, is a very basic dolerite, coming 
between the normal dolerites and picrites. In minerals a similar 
transition is to be noted. The andesites are rich in hypersthene, 
the dolerites rather richer in augite, while olivine and brown mica 
occur in the picrites. The author believed that the felspars 
became most basic in the more basic rocks, but he had not yet fully 
investigated this point. Another curious point was that the mineral 
aggregates in the glomero-porphyritic andesites are practically pieces 
of the ophitic dolerites. The determination of the specific gravities 
gave a similar sequence, the lighter rocks having been intruded last. 
Each of the irruptive rocks occurred in laccolites along the main 
anticline of the district, and also in the dykes and fault lines. 
III.—On tur Lower Carpontrerous Rocks of GLOUCESTERSHIRE.* 
By E. Werueren, F.G.S., F.C.8., F.R.M.S. 
N Gloucestershire there are two Coal-fields, namely, that of Bristol 
and the Forest of Dean. The Carboniferous Limestone Series 
of Gloucestershire was long ago divided by Sir H. De La Beche 
as follows: 
Upper MIxtTurE ofr SANDSTONES. 
Clifton. Forest of Dean. 
Feet. Feet. 
Warlssandeliimestonesy sre, css ce ce) tes 400 146 
CentralBRortionsa me eee eee estas Pee e438 480 
NRO WET ODALESI i isetdy ket tess: GSAD BMS A ioea.y LS 500 165 
338 791 
The author has proposed some detailed alterations with regard to 
the Bristol Coal-field which are stated in the Quart. Journ. Geol. Soc. 
for 1888, p. 187, but the above divisions have been generally accepted 
under the terms Lower Limestone Shales, Carboniferous Limestone, 
and Upper Limestone Shales. Professor Hull has given a classifica- 
tion of the Carboniferous Series throughout the country (Quart. Journ. 
Geol. Soc. 1877), based on the various stages which occurred during 
the deposition of the rocks. The author supports the principle of 
that classification, and is of opinion that the Lower Carboniferous 
rocks of Gloucestershire might be correlated with the same formation 
in the North of England. If this could be done, it might be possible 
to adopt terms for the respective stages which would apply to the 
North and South of England, and thus avoid the complication of 
terms now in use. 
_ The author then recited the stages which occur in the Carboniferous 
Limestone of Gloucestershire. Above the Old Red Conglomerate 
there appears a series of sandy beds which are best developed in the 
Forest of Dean. These consist of micaceous green shales and red, 
purple and yellow sandstones. Some are calciferous and readily 
effervesce when treated with acid. No fossils have been found, but 
quartz pebbles occur in some of the beds. 
The strata just referred to pass up into limestone and shales, the 
1 Read before Section C. (Geology) British Association, Bath, September, 1888. 
