1866.] PIKE " HEAVES " IN PENHALLS MINE, 535 



arrangement of the scales corresponds very closely with that seen in 

 the foot of the living Alligator ; many of them run across the foot in 

 oblique lines, as is common amongst living Crocodilians, leaving no 

 room to doubt that they represent true scales, and not irregular 

 tubercles, such as are seen on the skin of some Batrachians. Traces 

 of other impressions of feet occur on the slab, particularly an im- 

 perfect one with much larger and more oblong scales, especially under 

 the heel ; and this difference is so very similar to what is seen in the 

 fore and hind feet of many Saurians, that Prof. Williamson believed 

 that they did not belong to a Batrachian animal at all, but that they 

 were Saurian, if not Crocodilian, in every feature. 



4. A Description of some remarkable '' Heaves " or Throws in 

 Penhalls Mine. By J. W. Pike, Esq. 



(Communicated by C. Le Neve Foster, D.Sc, BA., F.a.S.) 



This mine is situated in the parish of St. Agnes, in the county of 

 Cornwall, and stands on the sea-coast, three or four hundred yards 

 from the edge of a bold precipitous cliff rising to a height of 300 

 feet above the sea-level. 



Pryee, in his valuable old book * Mineralogia Cornubiensis,' and 

 Carne and Hawkins in papers read some forty years ago before the 

 Koyal Cornwall Geological Society, together with many other writers, 

 refer to the heaves of the celebrated Pink lode, which is now a part 

 of Penhalls Mine. 



A paper was also read in 1815 before this Society, by Mr. John 

 Williams, entitled " Account of some Eemarkable Disturbances in the 

 Veins of the Mine called Huel Peever," the appearance of the 

 lodes in which mine present the nearest approach to the dislocations 

 in the Penhalls district. 



The nature of the ground or " country " is a light-grey, distinctly 

 stratified " killas" (the clay-slate of many geological writers, though 

 not a cleaved rock) with a pretty regular dip towards the north of 

 from 20° to 25°. 



In the immediate neighbourhood of the workings the ground is 

 traversed by : — 



1. Four or five tin-lodes, varying from 4 feet to a few inches in 

 width, dipping north at about the same angle as the killas, and com- 

 posed of the oxide of tin, with a little iron and copper pyrites in the 

 middle, — the walls or outsides, locally called capel, being a hard grey 

 killas with quartz and schorl. The only distinction between the 

 different lodes is in the appearance of the tin-stone, which varies in 

 the size of the grain and in colour. 



2. Three or four " downright " lodes averaging a foot in width 

 and running east and west. Their composition is something between 

 the tin-lodes and the " gossans ;" indeed in depth they generally 

 decrease in size and pass into gossans. 



3. Numerous ** gossans"* (lodes or veins), varying from a few 



^ A gossan in most parts of Cornwall consists very largely of an oohreous 

 VOL, XXII. — part I. 2 



