GEOLOGY. 329 



being white or gray in color and are associated with much mica-schist. 

 Other observers have described, in the region of the Upper Himalayas^ 

 syenitic gneisses resembling those of the peninsular type, succeeded by 

 various crystalline schists, with greenstones and soft talcoid slates. 



The Eozoic rocks, to which Hicks, in Wales, gave the name of Pebid- 

 ian, were some j-ears since compared lithologically with the Huronian. 

 Hunt, in pointing this out, after his comparative studies in the British 

 Islands, referred certain crystalline schists in eastern Ireland to the 

 Montalban series, which, as he had previously shown, is represented in 

 Donegal and in the Scottish Highlands, where Pebidian rocks are also 

 largely displayed. Hicks has since found there a series of crystalline 

 strata, which succeed the Pebidian, and which he has called Upper 

 Pebidian. These, as they are the predominant rocks in the Grampian 

 Hills, he proposes to designate the Grampian series. They consist in 

 large part of tender gneisses or granulites, with mica-schists, and accord- 

 ing to Hunt have the lithological characteristics of the Montalban series, 

 as seen in the Alps and in North America. 



CaUaway has contributed important observations to the question of 

 the age of the younger gneisses found in northwestern Scotland, in 

 Dunness, where they are found in close association with an older gneiss 

 recognized as Lewisian (Laurentian), a quartzite, a limestone with a 

 lower Paleozoic (Arenig) fauna, and a younger flaggy gneiss. This 

 latter, regarded by Nichol and others as pre- Cambrian, has been by 

 Murchison and his followers supposed to overlie the fossiliferous lime- 

 stones, and to consist of more recent or so-called Silurian strata in an 

 altered condition. Callaway has shown that the evidence of this super- 

 position is defective, and that on the contrary we are forced to conclude 

 that the flaggy gneiss belongs to an older series which underlies uncon- 

 formably the limestones. The conclusion to be deduced from all the 

 observations up to this time seems to us to be that the crystalline strata 

 of the Scottish Highlands, regarded by the geological survey of Great 

 Britain as altered Paleozoic strata, include representatives of various 

 pre-Cambrian groups, including Montalban (Grampian), Huronian (Pe- 

 bidian), and Arvonian, to which series Hicks refers the hdlleflintcb 

 series found in Glencoe. 



Callaway has also described the pre-Cambrian rocks of county Wex- 

 ford in Ireland, and finds beneath, the argillites of the Longmynd group 

 with Oldhamia, rocks which he compares with the Pebidian and Dime- 

 tran of Wales and Anglesea. He maintains that there is here no evi- 

 dence whatever of a gradual passage, such as had been asserted, from 

 the crystalline to the uncrystalline series, either in Wexford or in other 

 localities examined by him, and elsewhere says : " every case of sup- 

 posed metamorphic Cambrian or Silurian has been invalidated by re- 

 cent researches, and we are driven to the conclusion that within the 

 English and Welsh area there is a i)resumj)tion in favor of the suftpo- 



