The Drift or Boulder Formation. 323 



several Inindreds of tons. These are usually imbedded in a 

 tough clay, and sometimes so cemented together as to require the 

 aid of blasting in order to proceed with the work. The boulders 

 are many of them of the same kind of rock as that which exists 

 in the neighbourhood, while a large proportion consist of materials 

 only known in some distant part of the country. These latter 

 are more rounded than the former, a consequence of the rough 

 usage they have received during their transportation from the 

 parent bed. The drift is often overlaid by beds of clay or sand, 

 containing a few or no boulders ; but where this is not the case, 

 and the drift constitutes the surface, then the farmer who owns the 

 field will find himself greatly annoyed by the innumerable round 

 stones that impede his plough. From such fields the boulders may 

 all be removed from the surface, and after a few years a fresh crop 

 will take their place, having worked up from the deposit of drift 

 below, which extends downwards to the solid rock. Stoney fields 

 are so common in Canada that they are not usually looked upon as 

 objects of curiosity ; and yet the question of how the stones came 

 there is the most curious one in the science of geology. If it could 

 be proved that they were created on the spot where we now find 

 tbem, there would be an end of the question ; but then the more 

 a person examines them, the more convinced he will feel that they 

 have been transported from some locality more or less distant. 

 It is not our purpose to enter into all the proofs, but we shall 

 mention a few of the most striking evidences that boulders are 

 what they appear to be, and are often called travelled stones. 



It has been already mentioned in this journal in several places, 

 that the Lawreucian Rocks occupy the northern frontier of Canadii, 

 while a broad stripe all along the southern margin, from the mouth 

 of the St. Lawrence to Lake Huron, is underlaid by the Silurian 

 and Devonian Formations, only concealed from view by the drift 

 which, with a slight admixture of vegetable matter, constitutes the 

 ordinary agricultural soil of the country. The principal excep- 

 tion is between Brockville and Kingston, where the Lawrencian 

 Formation comes down from the north, and crosses the St. Law- 

 rence into the State of New York. Were a person to journey from 

 the east towards the west along the base of the Lawrencian hills, 

 he would have continually upon his left hand the flat country, 

 underlaid by the sandstones, limestones and shales of the fossili- 

 ferous formations, and occasionally he would see places where 

 these are laid bare, and abut against the gneissoid rocks which 



