Reviews — The Oeology of the Lizard. 309 



in thick sills. Near the contacts the Dippin rock becomes identical 

 with crinanite even in the matter of grain-size. 



The sill of Kingscross Point must also be correlated with the 

 Dippin sill and with the crinanites. It differs from the Dippin rock 

 in carrying a much smaller quantity of interstitial analcite and 

 zeolites and in a finer grain-size. The felspars are approximately 

 equal to the titanaugites in bulk, but the individual crystals are 

 much smaller. The ophitic plates of titanaugite are pseudo-porphyritic 

 in a groundmass composed of closely packed laths of plagioclase. 

 The Kingscross sill has suffered a curious veining by a tachylytic 

 basalt, and has also developed pegmatitic variation-facies in which 

 analcite and other zeolites are very prominent. 



From Allport's description it is probable that the great sill which 

 caps the Clauchland Hills is also a crinanite. He says: "A typical 

 specimen from Dun Fion contains crystals of plagioclase beautifully 

 striated, augite and olivine in a remarkably fresh condition, magnetite, 

 a few plates of brown mica, a little apatite, and a clear amorphous 

 glass in the interstices of the constituents." ^ The " clear amorphous 

 glass " is almost certainly analcite. 



All the rocks described above are unquestionably Tertiary in age. 

 Very similar rocks, however, are to be found amongst the alkalic Late 

 Carboniferous or Permian eruptives of Ayrshire.* Most of the rocks 

 of this sub-province which are to be regarded as related to crinanite 

 are intrusive in the Permian sandstones and underlying lavas of the 

 Mauchline basin, and are associated with analcite-syenite. A good 

 crinanite from an intrusion at New Gilston, Fifeshire, has recently 

 been brought to my notice by Miss A. T. Neilson, of the Hunterian 

 Museum, TJniversity of Glasgow. 



I?,E"VIETV"S. 



I. — Geological Survey Memoir. 

 The Geology of the Lizard and Meneage. By Dr. J. S. Flett, 

 M.A., and J. B. Hill, R.N. 8vo ; pp. viii, 280, with 15 plates 

 and 10 text-illustrations. London: printed for His Majesty's 

 Stationery Office, 1912. Price 5s. 



MENEAGE, as we are told in the preface to this memoir, is an 

 old Cornish name for the Lizard promontory, south of the 

 Helford Eiver ; so that the name applies to the whole of the Lizard 

 area, but strictly speaking not to the northern margin in the 

 Geological Survey map, which includes Eosemullion Head on the 

 east and Breage on the west. The colour-printed map (Sheet 359) 

 shows clearly the line of demarcation between the igneous and 

 metamorphic Lizard Series and the mainly sedimentary series, which 

 in old days was known generally as 'killas'. This forms the 

 northern portion of the area, together with some intrusive and 

 interbedded igneous rocks, including a fringe of granite at Constantino 

 and a small tract at Breage. The two great rock-series appear to be 



1 Q.J.G.S. XXX, 563, 1874. 



~ Tyrrell, Geol. Mag. (V), IX, 124, 1912. 



