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MINERALS AND GEOLOGY 



Deposits of Glacial, Post-Glacial and more recent age are spread 

 very generally over the Silurian and Devonian strata of this district 

 a wide break in the geological succession occurring here as in other 

 parts of the Province. These deposits comprise in ascending order : 

 (i.) The Boulder-clay or Lower Drift formation; (ii.) the stratified 

 " Erie Clay " formation ; (iii.) The Saugeen Clay and Sand formation ; 

 (iv.) The Artemisia Gravel and (v.) the Algoma sand deposits; with 

 (vi.) a series of recent accumulations, proper. 



The Lower or true Drift Formation consists of a thick deposit of 

 unstratified clay, holding Laurentian and other boulders. It appears 

 to be essentially a Glacier formation, derived in chief part from the 

 grinding action of ice on the surface of the subjacent rocks. As a 

 rule, it is greatly concealed from observation; and much of its 

 original substance has undoubtedly been removed, or otherwise re- 

 arranged in the form of succeeding deposits, by the subsequent action 

 of water. The Upper Drift deposits consist principally of dark blue 

 or gray calcareous clays, arranged in distinct layers, and containing, 

 as a rule, numerous stones and boulders, but no shells or other fossils. 

 These "Erie clays" yield white or light-yellow bricks. In places, as 

 near Brantford, etc., their planes of stratification are greatly con- 

 torted. Good displays occur along the north shore of Lake Erie 

 generally ; also near Clark Point, etc., and adjacent coast of Lake 

 Huron ; and at Woodstock, St. Mary's, London, and elsewhere 

 throughout the district. 



The Lower Fresh-water deposits, or " Saugeen clays and sands," 

 where in contact with the "Erie" or underlying boulder-holding 

 clays, commonly rest on the denuded surface of the latter. The 

 clays present a very general brown colour, and al though more or ]ess 

 calcareous, they yield, as a rule, red bricks. All are distinctly strati- 

 fied, and, in most cases, boulders are but sparingly present in them. 

 Good exposures, showing the blue or Erie clay below, occur more 

 especially near Port Talbot and Port Stanley on Lake Erie. Others 

 may be seen around Woodstock ; and also between Clark Point and 

 Port Frank on Lake Huron, as well as at various spots on the 

 Saugeen, around Walkerton, and throughout the township of Brant 

 generally. Layers of sand and gravel are commonly associated with 

 these clays; and a deposit of coarse gravel with boulders the 

 " Artemisia gravel " of the Geological Survey extends largely 



