28 THE CAMBRIAN. 



In Mr Matthew's latest paper* he states that while in certain 

 parts of the Cambrian basin of St John the Acadian series (Para- 

 doxides group) rests directly on the Laurentian, in tracing the beds 

 to the eastward they are found to be separated from the Laurentian 

 by a band of conglomerate, shales, sandstones, and flags of purplish, 

 reddish, and greenish colours. Some parts of these beds I have had 

 the pleasure of seeing in company with Mr Matthew. They consti- 

 tute what he has termed the Basal Cambrian series, and attain to a 

 thickness of 1200 feet. They are regarded as the equivalents of the 

 Caerfai group of Hicks and of the so-called Sparagmite formation of 

 Norway, and the upper part is supposed to correspond with the lower 

 portion of the Maimel's brook beds of Newfoundland. These lower 

 beds, holding what has been called the OleneUus fauna, from the 

 occurrence of large Trilobites of tliat genus, are now regarded as Lower 

 Cambrian,-}- and the Georgia slates of the Province of Quebec are 

 included in its upper part. We should thus have in ascending 

 order: — 



1. Basal series of Matthew, Lower Cambrian or OleneUus series. 



2. Acadian or St John series, Middle Cambrian or Paradoxides 

 series. 



3. Potsdam or Upper Cambrian.^ Peltura beds of Mire, Cape 

 Breton, Kelly and Little Bell Island beds, Newfoundland, and possibly 

 portions of Upper Member of St John group in New Brunswick. 



The descriptions given in pages 637 et seq., it will be observed, 

 refer mainly to the second of the above divisions, and many additions 

 to the fossils, as well as revision of the nomenclature, will be found in 

 the papers of Mr Matthew above referred to, and in a memoir by Mr 

 Walcott in the publications of the U.S. Geol. Survey. § 



VIII. THE HURONIAN. 



In the typical area of Lake Huron, as originally described by Logan 

 and Murray, II this system rests unconformably on the Lower and 

 Middle Laurentian, and presents a great contrast in point of mineral 

 character to these formations. It is comparatively little disturbed, 

 and is elastic rather than crystalline in character. This point has 

 been well insisted upon by Dr Bonney and by Mr Irving in recent 



* Trans. Royal Socj. of Canada, vol. vii., sec. 4, page 135. 



t Walcott, Am. Jl. Sci., May 1889. 



t Matthew prefers with Hicks to consider the Paradoxides beds as Lower Cambrian ; 

 dividing the whole system into two main divisions (American Geologist, Sept. 1889, 

 p. 139). 



§ Bulletin, No. 10, 1884. || Geology of Canada, 1863. 



