124 SUPERFICIAL GEOLOGY OF DUNDAS VALLEY. 



also be reasonably inferred that the conglomerate beds, with the over- 

 lying silts and clays are the results of a period succeeding the glacial 

 period, in which the blue clay was laid down 



These beds may be, and are in all probability the results of a 

 closing up of the mouth of the stream flowing down the valley, and 

 a general flooding of the district for a great number of years. 



The breaking of the bank closing up the mouth of this stream, 

 after the lowering of the waters of the lake, would drain the valley 

 to the extent we now find it, and also leave the channel occupied, as 

 we now find it, by the marsh. When we consider the great depth of 

 the old mouth of the canal, this seems all the more probable. 



The question how is it that the beds are alternately coarse gravel, 

 mud pebbles and sand, of various degrees of fineness, naturally comes 

 up to the observer's mind. 



This variation, accepting the foregoing theory as correct, would 

 lead to the conclusion that then as now, the waters of the lake were 

 subject to periods of storm and calm. In fine weather, when the waters 

 of the lake were at rest, they would have less force of action, and as a 

 consequence would only be able to move the finer materials, but at 

 times of storms the force of water breaking over the shoal, would carry 

 the pebbles high up on it and deposit them where we now find them. 



Mr. Sanford Fleming, in the Canadian Journal, New Series, Vol. 

 VI, page 257, describes another such ridge, known as the Davenport 

 Ridge, in the Township of York. He says "the gravel deposit can be 

 traced over a considerable area, but unlike the terrace in its windings 

 into the interior, the gravel is found only in a uniform straight direc- 

 tion, and that generally parallel to Lake Ontario. 



" The gravel is not deposited in horizontal beds as is generally 

 the case with subaqueous formations, nor is it laid in thin beds dip- 

 ping southerly or from the shore towards the water, as if they had 

 been thrown up one over another on the inclined plane of the bench 

 by the storms of the former lake. On the countrary we find the 

 gravel invariably deposited in the the opposite direction, that is to 

 say, dipping away from the lake and in some instances, nearly at 

 right angles to what may have been the plane of the beach." 



Mr. Fleming's theory as to the formation of the Davenport 

 Ridge is, that the gravel was washed out of the terrace into the posi- 

 tion it now occupies, and that being at one time under and at 



