Revieios — Dr. Tempest Anderson — Volcanic Studies. 163 



crowned the whole, has been denuded away, and the more durable 

 rock, forming the neck, alone remains. 



The delineation of columnar structure in basalt has received great 

 attention from Dr. Anderson, and his efforts in this connection have 

 been very successful. Central France, the coast of Antrimr and the 

 Eifel are amongst the regions which he has specially selected. Let us 

 take, for instance, the " Valley of Jaujac in the Ardeche" (pi. xxxviii). 

 The subject has attracted the notice of many a geologist, and our 

 readers may remember that the " volcanic cone and basaltic lava- 

 current of Jaujac " constitutes the frontispiece of the second edition 

 (1858) of Scrope's ''Volcanoes of Central France." Oar author's 

 photograph deals with a limited portion of Scrope's original picture. 

 PL xxxviii, in our opinion, serves to illustrate the character of this 

 work on volcanic studies, v^^here a landscape of extreme interest and 

 beauty is also rendered most instructive as a geological section, 

 showing columnar basalt at the bend of the river. There seem 

 to be two beds, totalling 150 feet vertical, but the author regards 

 these as the result of one lava-stream, "the appearance of division 

 being produced by the line of junction of the columns of which 

 both portions are composed, and which owe their origin to cracks due 

 to contraction by cooling of the upper and lower surfaces respectively, 

 and their extension inwards until they meet." 



Whilst dealing with the subject of columnar basalt attention may 

 be directed to remarkable examples in the Eifel district (pis. Ixxviii, 

 Ixxixa, and Ixxx). The Kasekellar is a noted instance, where the 

 basalt is massive above and sub-columnar below, breaking up into 

 short joints like Dutch cheeses, whence the name. Equally remark- 

 able in a different way is the structure of the Hummelsberg, showing 

 a system of fine vertical columnar jointing, which almost reminds 

 one of fibrous serpentine (chrysotile) on a large scale ; whilst the 

 disposition of the basaltic column in the Mindenberg is held to 

 be an example of cooling from the top; the structure is very 

 peculiar. There are also two very effective pictures (small) of the 

 Griant's Causeway, whilst the relations of the basalt to the Cbalk 

 on the coast of Antrim are fully depicted and their historical 

 significance dealt with in the text. 



There remains one very extensive subject, viz. Iceland, to which 

 thirty plates are devoted. To do anything like justice to this part of 

 the work would almost require a separate notice. Dr. Thoroddsen 

 has animadverted lately in very severe terms on the majority of 

 modern works on Iceland, as consisting largely of personal details. 

 Nothing of the sort can be alleged against Dr. Anderson. He 

 appears to have spent two Summers there, and his photographs 

 tell their own story of this treeless land of frost and fire, with 

 occasional assistance by way of interpretation in the text. It is 

 a triumph of the positive method as against the flood of speculation 

 with which geological literature is occasionally inundated. 



The Hafragil's Foss in the valley of the Jokulsa (pi. xlix) is 

 a fine specimen of terrace cutting through horizontal volcanics of an 

 older series. This river may be regarded as typical of Iceland, since 



