Geolocrical Address at Manchester, 401 



to 



" For hitharto the order of the geological succession even, as 

 seen in the geological map of England and Wales, or Ireland, as 

 approved by Sir Henry de la Beche and his noble coadjutors, 

 Phillips, Ramsay, Jukes and others, admits no older sediment 

 than the Cambrian of North Wales, whether in its slaty condition 

 in Merioneth and Caernarvon, or in its more altered condition in 

 Anglesea. 



" The researches in the Highlands have however shown that 

 in our own islands the older palaeozoic rocks, properly so called, 

 or those in which the first traces of life have been discovered, do 

 repose, as in the broad regions of the Laurentian Mountains of 

 Canada, upon a grand stratified crystalline foundation, in which 

 both limestones and iron ores occur subordinate to gneiss. la 

 Scotland, therefore, these earhest gneissic accumulations are now 

 to be marked on our maps by the Greek letter alpha^ as preced- 

 ing the Roman a, which had been previously applied to the low- 

 est known deposits of England, Wales, and Ireland. Though we 

 must not dogmatize and affirm that these fundamental deposits 

 were in their pristine state absolutely unfurnished with any living- 

 things (for Logan and Sterry Hunt in Canada, have suggested 

 that there they indicate traces of the former life,) we may con- 

 clude that in the highly metamorphosed condition in which they 

 are now presented to us in North- Western Britain, and associated 

 as they are with much granitic and hornblendic matter, they are 

 for all purposes of the practical geologist, ' azoic rocks.' The 

 Cambrian rocks, or second stage in the ascending order, as seen 

 reposing on the fundamental gneiss of the north-west of Scot- 

 land, are purple and red sandstones and conglomerates, forming 

 lofty mountains. These resemble to a great extent portions of 

 the rocks of the same a^e which are so well known in the Lono^- 

 mynd range of Shropshire, and at Harlech in North Wales, and 

 Brav Head in Ireland. 



*' At Bray Head they have afforded the Oldhamia, possibly an 

 aZ^CT, while in the Longmynd in Shropshire, they have yielded to 



gestion, the word " Laurentian" in compliment to my friend Sir Wm. 

 Logan, who had then worked out the order in Canada, and mapped it 

 on a stupendous scale. I stated, however, at the same time, that if a 

 British synonym was to have been taken, I should have proposed the 

 word " Lewisian," from the large island of the Lewis, almost wholly 

 composed of this gneiss. 



Can. Nat. 5 Vol. VI. No. 5. 



