Serpentinite of the Lizard. 285 



tions of the zigzag edge and the two limbs of the ridges strictly 

 correspond with the two cleavages above mentioned. Obvi- 

 ously, then, there is an intimate connexion between these three 

 formations ; and no one can observe the ridges without feeling 

 convinced that they were once integral portions of the adjacent 

 mass of saponite, also that the presence of calcite in the inter- 

 mediate spaces is an interpolated phenomenon. Moreover, on 

 further consideration another conclusion irresistibly forces 

 itself into notice — that the intermediate spaces were once oc- 

 cupied with saponite, which, having been removed, has under- 

 gone replacement by the calcite now occupying them. As in 

 the case of an outlying reef of rock that has been separated 

 from the mainland by the gradual removal of an intermediate 

 mass of rock, and the latter replaced by the sand now occupy- 

 ing the denuded space, so it must have been with the outlying 

 ridges of saponite and the calcitic interspaces. 



It may be suggested with regard to the latter interspaces, 

 that they are the result of cracks, widened by some cause or 

 other, and subsequently filled up with a deposition of calcite ; 

 but this is completely disproved by their being shaped like the 

 ridges. The portion corresponding with, say, the downward 

 limb of the ridges might be produced by a widened crack ; but 

 in such a case the origin of the other or transverse portion must 

 be the same. Again, the slightest reflection on the integrity, 

 relative position, and uninterrupted connexion of the two limbs 

 of the ridges must deprive the suggestion of every probability. 



Guided by what we have very frequently observed in ophite 

 (clearly leading to the conclusion that serpentine has been gra- 

 dually replaced by calcite), we have no hesitation in offering, 

 in general terms, the same explanation for the case under 

 notice *. 



* We would suggest the following as 

 the particular way in which it may have 

 been produced. As the saponite is in- 

 termittently cleaved, it is consequently 

 liable to be disintegrated or decomposed 

 here and there where the cleavage is pre- 

 sent, and to retain its compact condition 

 where there is no such divisional structure 

 developed. Let it be conceived that a 

 mass of saponite was intermittently 

 cleaved, as in the annexed woodcut (which 

 it will be seen is a fac simile in outline of 

 fig. 5) ; the cleaved portions will thus be 

 rendered easily affected bv dissolving 

 agencies (e. g. a carbonated solution), sS Diagram ^showing a niass^ oi 

 that while their saponite is removed and f P on * e with cleavage in- 

 replaced by calcite, the same substance termittently developed, 

 will remain untouched in the uncleaved The non-lineated portions 

 T . Art - 11s , consist of uncleaved sapo- 

 poiuons. mtGi 



