242 PROCEEDINGS OF THE COTTESWOLD CLUB 



their origin igneous and plutonic, not igneous and sedi- 

 mentary. The apparent stratification is due to pressure, 

 not to deposit under water. The crystalhne condition is 

 not superinduced upon an original fragmental structure, 

 but is itself either original or a recrystallization under 

 new conditions. To make the theory clear, a few details 

 are necessary. 



The Malvern crystallines were once an igneous complex, 

 that is to say, they were a mass of igneous rocks, chiefly 

 a granite, and two or three varieties of diorite, which were 

 intruded into each other in veins, dykes, and masses. The 

 diorites form by far the largest part of the range, and may 

 be well seen in the quarries at North Malvern, in a large 

 quarry in the Hollybush Pass, and indeed almost wherever 

 rock is exposed. The granite is easily distinguished from 

 the dark-green diorites by its pink or reddish colour. It 

 usually forms veins in the diorite, but at the northern end 

 of Swinyard's Hill, and at several other localities, it appears 

 in considerable masses. The veins vary in thickness from 

 several yards to a scarcely perceptible line. Sometimes 

 they occur in great numbers very close together, and give 

 the rock a distinctly banded appearance. 



After the rocks of the complex had consolidated — or 

 the greater part of them — the whole mass was subjected 

 to enormous pressures, acting for the most part along a 

 north-east and south-west line, which caused the rock 

 here and there to give way, and flow along planes at right 

 angles to the direction of the compressing force. I say 

 " flow," but it will be readily understood that the flow 

 of a solid differs from that of a liquid. A solid body 

 yields to the pressure by fracturing ; it can give way 

 to the new stresses only by breaking into fragments, and 

 these, as the crushing continues, are forced to shear and 

 slide over each other. They take the form of lenses, 

 thickest in the middle, and thinning towards the edge. 



