Hevieics — Geological Map of the British Isles. 417 



These chronoloo;ical results Mr. Goodchild offers only as a rough 

 Rpproximation to the real truth, not by any means as a final answer 

 to a difficult question. The seven-hundred-million years carry us 

 back to the beginning of the Cambrian Period, but not to the com- 

 raencement of life on the Earth. The Lower-Cambrian fauna already 

 contained representatives of all the chief forms of Invertebrate life ; 

 and probably the earliest preceding organisms existed as far away 

 from that period as that period is from the present. 



II.— Geological Map of the British Isles. (Edinburgh and 



London : W. and A. K. Johnston, 1896.) 

 rilHIS map, originally compiled by Sir Archibald Geikie, LL.D., 

 JL etc., Director-General of the Geological Survey of Great 

 Britain, has been revised and extended by Alex. Johnstone, F.G.S., 

 etc. It is on the scale of 1,890,000 of nature, or fourteen miles to 

 an inch. It is an excellent wall-map in its general aspect ; and at the 

 same time is plentifully inscribed, in small writing, along the coastlines 

 with geological and mineralogical notes relating to the interior. 



This new edition of the Geological Map of the British Isles, to 

 which the " Mineralogical Geology " noticed on p. 418 is an adjunct, 

 gives the systematic groups of formations in their several areas, 

 strongly coloured and distinctly indicated by successive numbers. 

 The grouping we give below. As many of the subdivisions are 

 included in the general hard and fast colour of the group, their 

 individuality is lost in the map, although often traceable in one or the 

 other of the forty-five sections (either diagrammatic or generalized), 

 which usefully occupy available spaces on the map-sheet. 



The Quaternary (24, 23) is not mapped. 22, Pliocene or Crag. 

 (21, Miocene, absent.) 22, Oligocene. 19, Upper and Middle; and 

 18, Lower Eocene. 17, Upper ; and 16, Lower Cretaceous. 

 15, Upper, Middle, and Lower Oolite. 14, Lias. 13, Triassic, 

 including Ehsetic. 12, Permian (a dark-brown, printed inad- 

 vertently in two tints, above and below the latitude of Hartlepool). 

 11, Coal-measures. 10, Millstone Grit and Devonshire Culm. 

 9, Carboniferous Limestone Series. 8, Upper Devonian and Upper 

 Old Red Sandstone. 7, Middle Devonian. 6, Lower Devonian and 

 Lower Old Ked Sandstone. 5, Silurian. 4, Ordovician. ^ 3, 

 Cambrian. 2, Newer Pre-Cambrian and Archaean, or Huronian. 

 1, Older Pre-Cambrian and Archeean, or Laurentian. If it were not 

 for their numbering, some of the colours would probably be mis- 

 taken on the map one for another — such as 20, 19, 18, and 8, 7, 6 ; 

 also 11 and 4. 



Some extra care has been taken in the definition of the Igneous 

 Rocks both on the map and in the explanatory list with the " Table 

 of Systems and Formations," thus : — Acidic : granite, G ; syenite, 

 S; felsite, F; trachyte, T; obsidian and pitchstone, P. Inter- 

 mediate : diorite, D ; andesite, A ; lamprophyre, L ; and phonolite. 

 Basic : dolerite and basalt, B ; gabbro, Gb ; picrite, Pc ; serpentine, 

 Sr ; and tachylite. 



This map will be found very useful in lecture-room, study, and hall. 



DECADE IV. — VOL. IV. — NO. IX. 27 



