August 10, 1883.] 



SCIENCE. 



169 



1. — Diagram plan shmcing how the Cambrian basement beds creep over the'earious ditisions of the archean 

 between Bawjor and Carnarvon {Iluglten). 



CAKNAnVOS. ' liANGOn. 



■ Cambrian, 

 b, Kandtttone nnil shale of Cambrian, 

 a, Conglomt»rftle aud grit of Caiubri, 



baiivmont beds. 

 •1, Twt Hill; •2, Yacyborwen; •a, Careggoch; •4, Llandeloiolcii; *ii, Tymawr; *6, Brithdir; 'T, Hcndrcwen: 'S, Bryniau Baogor. 



-^. Bryniau beds ) Bani;or eroup ( = Pe. t C, Crug beds ^ Carnarvon group { = Diine- 

 y;, Dinorwig beds t bidian, etc.). | /J, Twt bids \ lian). 



i. — Diagram nection east and west across Bryniau Bangor. 

 Lengtli of section about one mile (Hughes). 



afi a^ a^ a^ 



b, Baiigor beds (upper Pebidian) ; a^. Conglomerate and sandstone (basement bed of Cambrian) ; a', Sandy mudstone; a'. Finer 

 fetspatbic mudstone; «■*, Pale green feispatliic mudstone; a*, Cleaved and contorted felspatliic mudstone; «■», Purple and green 

 fine mudstone and slate; o^, Fine sandy (lags, like the Bray beds, purple, and here and there green, passing up into brown ; 

 a", Even-bedded thin gray sandstones ; a**, Banded tlags, passing up into a>^. Black slates. 



S. — Diagram-section showing the sequence of rocks from Carnarvon to Snowdon. 



Length of section ten miles (Hughes). 



Slate Snowdon. 



Cwmglo. Llyn Padarn. quarries. I.lyn 1 



Arc/ieitn. 

 A, Carnarvon group (Dimelian) ; Bt Dinorwig group, 

 (f, Conglomerate and s:indstone (basement bed of Cambrian); b. Lower and middle portions of Cambrian, not subdivided, but 

 probably including Harlech, Menevian, Lingula flags, and Tremadoc beds; c, Arenig; p, Pisolltlc iron ore; r/, Bala group, with 

 subordinate volcanic beds; F, Faults; x. Broken ground; /), Dikes. 



are merely intrusive masses or altered beds of Silu- 

 rian and Cambrian age. The basal conglomerate in 

 this area consists in places almost entire! j- of quartz- 

 felsites, at other points of a mixture of granitoid 

 (true Dimetian) and felsite rocks, and in some cases 

 of schists. I may further mention with regard to 

 the crystalline schists in Anglesey and in Scotland, 

 supposed by the Geological survey also to be of Cam- 

 brian and Silurian age, that the recent researches of 

 Bonney, Callaway, Lapworth, and myself, tend to 

 make it certain that they are ail, like the similar 

 rocks in America described by Dr. Sterry Hunt and 

 others, of pre-Cambrian age. Henrv Hicks. 



Hendon, N. W., London, 

 July 5, 1883. 



Silurian strata near Winnipeg. 



Presuming that it may be of interest to some read- 

 ers of SciF.NCK to read something on the geology of 

 a locality near Winnipeg, I take pleasure in furnish- 

 ing information, hitherto unpublished, concerning 

 an outcrop of Silurian strata in this- part of the 

 north-west. This interesting exposure occurs a short 

 distance from Selkirk, situated some twenty-one 

 miles north of Winnipeg on the Canadian Pacific 

 railway, and near the Kcd Kiver. 



At this place a i|uarry was opened about a year 

 ago, which, on examination, affords many attractions 

 to a student of science. Fossils belonging to some 

 sixteen species are readily obtained, not only in the 



