TRANSACTIONS OF THE SECTIONS. Il7 



of whose labours mainly the limestones are the result, required a pure oceaa 

 imcontaminated by sediment. This was the case v/iili the ocean in Derbyshire ; 

 but in the north it was charged with sand and mud, which interfered with, and 

 idtimately oTerpowered the organic agents. Hence the essential distinction be- 

 tween limestones and all other binds of sedimentary strata was strongly insisted 

 upon, the one being directly antagonistic to the other. 



The author next showed that we could trace at inteiTals the north and south 

 coasts of a barrier of land which stretched from Wales to the Gennan Ocean diuing 

 the Carboniferous period. (See Map, Journ. Geol. Soc. vol. xviii.) 



South of this bamer there exists another carboniferous tract, represented by the 

 coal-fields of South Wales, Somersetshire, Gloucestershire, and possibly of one imder- 

 lying the cretaceous rocks and stretching into Belgium. This tract was separated 

 by the barrier fi-om that of Central England, and the sediment had been carried from 

 a different direction. The isometric lines, di-awn in accordance with the vaiiations 

 of thickness as described by Sir H. De la Beche, showed that the sediment had 

 been carried by a current coming from the W.S.W., while the calcareous group 

 had been propagated in greatest abundance from the east ; so that on the south 

 side of the barrier there was as great a conti-ast in the distribution of the calcareous 

 and sedimentaiy strata as on the north side. 



_ The author next proceeded to remark that America exhibited phenomena of a 

 kind similar to those here described in Britain. As had been shown by Sir C. Lyell 

 and Prof. Eogers, the sedimentaiy strata augmented towards the ]Sf.E. in Nova 

 Scotia, and became attenuated in the basin of the Mississippi (in which direction 

 the limestones increase in vertical dimensions), proving that the sediment had been 

 drifted from the north-east. The autlior contended that the same great continent 

 of the North Atlantic had been the progenitor of the carboniferous strata of both 

 America and Britain, and that its shores were swept by a north-east current in the 

 western hemisphere, and by a north-west cm-rent in the eastern. 



On ilie Progress of the Survey in Ireland. 

 By Professor JxtkeSjF.G.S., Local Superintendent of the Irish Survey. 



On the Relation of the EsMale Granite at Booth to the Schistose Eocl-s, with 

 Bemarl-s on the General Metamorphic Origin of Granite. By J. G. Mae- 

 snAiL, F.G.S. 



In a paper read by me at the Meeting of the British Association at Leeds in 

 1858, on the Geology of the Lake District, I endeavoiued to establish the following 

 propositions : — 



1. That the older slate rocks of Cumberland and Westmoreland, the Skiddaw clay- 

 slate, and the greenstone slate series, have been generally subject to the metamor- 

 phic action of heat, pressure, and moistm-e. 



2. That some of the slaty beds being more fusible than others above or below 

 them in the series, have been more acted on than the less fusible beds, and changed 

 into poi-phyries, whilst the others have only been hardened ; and hence an alterna- 

 tion of stratified and unstratified beds has resulted, though the whole series were 

 originally soft stratified deposits. 



3. That the granites and syenites of this district are as truly metamorphic rocks 

 as the porphyries — the change to the crystalline structure being merely the last 

 term, the extreme residt of the metamorphic action of combined heat, pressm-e, and 

 moisture, followed by veiy slow cooling ; and that these rocks, when found in mass, 

 are not eruptive or intrusive, but altered beds of slate rock in situ in their natural 

 position as regards other beds in the series. 



4. That the forces which have elevated, contorted, and fractured the strata of 

 this district have not been the eruptive energies of the gr-anites and syenites, but 

 have been produced by the expansion or contraction of the earth's crust, by heating 

 or cooling on a large scale, and chiefly shown in great lateral thnists, producing 

 flexures and fractures in the weaker portions of the crust of the earth. 



