422 Reviews — Elements of Mineralogy. 



Paljeozoic succession includes both Ordovician and Silurian rocks, 

 and i-ests unconformably upon a much older series of hornblendic 

 and pyroxenic gneisses and schists, into which masses of granite 

 were intruded in pre-Silurian time. 



The succession may be tabulated as follows : — 



G. CoKRYCRoAK Group : TaraMuon (Gala Facies) : — Variable 

 green and grey flags and shales with purple and green grits and 

 conglomerates. ( Undivided.) 



B. Little Rivkr Group : Llandovery (Birkhill Facies) : Lime 

 Hill Beds : — Black, blocky, micaceous mudstones, with light-coloured 

 calcareous bands. Zone of Monograptus Sedgwickii with subzone of 

 Petalograpti. — Mnllaghnabuoyah Beds: — Variable grey shales and 

 flaggy shales with pyritous spots and a few dark bands. Zone of 

 Monograptus triangulatus (sp. ?). — Edenvale Beds: — Smooth, grey 

 shales witli black mudstone bands. Zone of Ilonogrnptus tenuis. — 

 Upper Slate Quarry Beds : — Dark cuboidal mudstones, hard and 

 calcareous. Zone of the Dimorpliograpti. — Tjower Slate Quarry 

 Beds: — Soft, blue-grey, papery, micaceous flags. Zone of Diplo- 

 graptus modestus. — Ciocknagargan Beds: — Smooth, grey, pyritous 

 shales. Zone of Cephalograptus acuminntus. 



A. Desertcreate Group: Ashgillian Drnmmuck Facies: 

 Upper Tirnaskea Beds: — Smooth, banded, green and dark mud- 

 stones. Zone of Dicellograptus anceps. — Lower Tirnaskea Beds : — 

 Tough, blocky, calcareous grits. Zone of Dicellograptus complanatus 

 and Phacops mucronatns. — Upper Killey Bridge Beds: — Soft, cal- 

 careous, grey mudstones, with Remopletiridcs and Diplograptus 

 tnmcntus. — Ijower Killey Bridge Beds: — Soft, ferruginous blue or 

 yellow mudstones, witii many Trinucletis and Ampyx. — Upper 

 Bardahessiag Beds : — Hard and calcareous flags and grits with 

 Lichas, Fhdcops hibernicus, Stcmrocephalus, etc., and Strophov)en(i. — 

 Lower Bardahessiag Beds : — Softer, uncompacted grits, sandstones, 

 and conglomerates, with large Strophomenn and occasional Orthis. 



The Desertcreate Group finds its closest parallels in the Drummuck 

 Beds of Girvan, while the Little lliver Group is most like the 

 Birkhill shales of Moffat. The whole series is overlain uncon- 

 formably by the Dingle Beds of the local Old Red Sandstone, and, 

 with the formation, has been folded into a remarkable series of 

 shallow isoclines trending a little south of east and north of west and 

 having a general southerly pitch. The total thickness of Desertcreate 

 and Little River Groups together does not exceed 500 feet. 



I?, :e V" I IE AAT" S. 



L — Ele3ients op Mineralogy. By Frank Rutley, F.G.S. 

 Fourteenth edition, revised and corrected. Demy 8vo; pp. 251, 

 viii. (London : Thomas Murby & Co.) 



rpHLS little book forms one of the series of textbooks issued by 

 X the publishers to meet the requirements of the Science and Art 

 Department, and its popularity is sufliciently indicated by the fact 



