TRANSACTIONS OF THE SECTIONS. 55 



stances, he contended that these strata, and the inner concentric 2ones of mica-schist 

 and gneiss would be invaded by ramifying and anastomosing veins emanating from 

 the internal fluid, to an extent proportionate to the temperature; these veins (the 

 result of the intense heat which formerly traversed and melted down the walls of the 

 joints, and radiated thence laterally among the laminae of deposition), instead of 

 being passively injected among the bounding sedimentary or igneous rocks, were the 

 active instruments which fused and converted those rocks into trap, porphyry, or 

 granite, as the case may be ; these veins would thus convert the zone of gneiss into 

 incandescent lava, the mica-schist into gneiss, and a proportionate thickness of the 

 sedimentary strata into mica-schist; and if the vis a tergo of heat should be main- 

 tained, such transformations would progressively advance till the superincumbent or 

 outermost strata being reduced to their point of least resistance, they would neces- 

 sarily yield to the pressure or expansive force of the augmenting volume of the liquid 

 matter, and present all the phsenomena of a crater of elevation. From the whole 

 amount of his observations, taken round the granite of Dartmoor, Bodmin Moor, 

 &c, he considered that if Von Buch had not proposed the theory of "Elevation Cra- 

 ters," geologists would eventually have been constrained to have recourse to some 

 hypothesis of the kind to explain the appearances presented by those granitic domes. 

 With regard to the origin of the schist and slate rocks, a series of specimens might 

 be gathered from many localities in South Devon and Cornwall which would show 

 an insensible transition from the coarser volcanic grits and breccias into the finest 

 clay slate, every variety of which he had traced up to those more typical products. 

 Mr. Williams stated, that his inquiries had resulted in the conviction that granite, 

 gneiss, mica-schist, clay slate, &c. are no evidence of age or position in the geological 

 scale, but that they appertain to all formations, from the most ancient to the most 

 recent ; he considered gneiss and mica-schist were not simply " metamorphic " rocks, 

 but rocks in a particular or definite stage of fusion. The term " metamorphic" was 

 perfectly true so far as it went, but did not convey the entire sense which the facts 

 and circumstances of this class of rocks so manifestly conveyed. He therefore sug- 

 gested that they should be termed intermediate products, and granite, porphyry, trap, 

 breccia, grit, ash, chloritic, talcose, and clay slate, immediate products of volcanic 

 action. 



On some peculiar Inorganic Formations and Fossils of the Magnesian Lime- 

 stone. By Edwin Lankester, M.D. 



This communication was descriptive of a series of specimens placed on the table, 

 illustrating various appearances and forms assumed by the magnesian limestone. 



On the Occurrence of Boulders in the Valley of the Calder. By 

 John Travis Clay. 



In consequence of the information given by Lieut. William Alexander of Halifax, 

 at one of the meetings of the West Riding Geological Society, that in prosecuting 

 the works of the Manchester and Leeds Railway some pieces of granite had been 

 found at Hebden Bridge, the author proceeded to investigate the formation of the 

 alluvial deposits in the valley, and the result of the examination proved that boulders 

 of granite and other hard rocks exist in considerable abundance along a distance of 

 many miles. 



" The valley of the Calder along its whole course is bounded on both sides by 

 abrupt hills, which enclose a narrow and almost always level tract of land. The 

 hills are of the regular coal strata, and as far as I have been able to discover, are de- 

 stitute of a single boulder or even rounded pebble. The level portion, on the con- 

 trary, is entirely composed of removed matter, near the surface sand, clay and small 

 pebbles; but at about the depth of five feet there is a bed of boulders of a much 

 larger size, the majority of which are from the neighbouring rocks, but also contain- 

 ing many of granite, and others of similar origin. 



" The peculiarity of this deposit, when compared with that which occurs so ex- 

 tensively in the centre and eastern parts of Yorkshire, as well as in Lancashire, con- 

 sists in its being confined to this narrow stripe, frequently not a quarter of a mile in 



