18 



REPORTS ON TORONTO HARBOUR. 



of years which separate the present time from the epoch when the 

 Niagara flowed at a higher level." 



Thus, then, the Don, coeval with the Niagara, has flowed, according 

 to this great Geologist, for a period far too great for the imagination 

 to comprehend, and which one can scarcely ventureto name by years;* 

 even allowing that our historical knowledge of the past condition of 

 the Falls is far too meagre to estimate with any degree of precision, 

 the rate of their retrogression in former ages, yet we cannot but arrive 

 at the conclusion that the chronological age of the Niagara and conse- 

 quently of the Don, must be so enormously great, that one would think 

 even its fractional part would suffice for the removal of the hundreds 

 of millions of yards of matter by the latter river to the Lake, without 

 calling to its aid any unusual phenomena. 



Having thus shown that sufficient time may be granted, the Don 

 therefore supplies an adequate cause for performing and completing 

 long since the work assigned to it ; year after year during its early 

 history, slowly but constantly hollowing out a channel and removing 

 the former contents of its valley to the lake, the lighter and more 

 soluble matter being held for some time by the water, to be distributed 

 far and wide, the heavier particles on the other hand to be deposited 

 near its mouth, in the form of an extensive shoal or delta — the base or 

 ground-work of the Peninsula, on which again to be deposited a drift 

 from other causes and from another source. 



Second, That the Peninsula proper has been formed solely 'by the 

 mechanical action of the waves, that the sand and gravel of which it 

 is composed have been by this action gradually transported from the 

 eastward and deposited on the deltaic shoal of the Don, and that the 

 delta has thus been raised above the surface of the water and extended 

 westward far beyond its original limits. 



The effects produced by waves on a shore exposed to their action 

 are of various kinds, depending in a great measure on the nature of 

 the beach, the direction of the waves, and their mechanical force : if 

 the shore be of clay the action is entirely destructive, the banks are 

 undermined and continually caving in, the fine argillaceous particles 

 are taken up by the water, carried out and deposited after a time at 

 depths unaffected by the motion at the surface ; if the shore be of sand 

 or gravel the effects produced are quite different. "When the direction 

 of the waves is not at right angles to the beach a progressive action 

 results, and when the waves break point blank on the shore line with 

 sufficient force the action is destructive, in which case the banks are 

 broken down and the spent wave returns loaded with sand to be de- 

 posited outside of the breakers in the form of a shoal generally parallel 

 to the coast ; if the soil of which the banks are composed be a mixture 

 of clay and sand the action is both destructive and progressive, the 

 clayey particles are washed out and deposited in still water, while the 

 sand, gravel, and stones are left behind to be moved forward either in 

 one direction or another, and at a rate depending solely on the strength 

 of the impinging waves, and the gravity of the materials themselves. 

 On a rocky shore the effects produced are precisely similar, although 



* "Mr. Bakewell calculated that, in the forty years preceding 1830, 

 the Niagara had been going back at the rate of about a yard annually, 

 but I conceive that one foot per year would be a much more probable 

 conjecture, in which case 35,000 years would have been required for 

 the retreat of the Falls, from the escarpment of Queenston to their 

 present site, if we could assume that the retrogade movement had been 

 uniform throughout. This, however, could not have been the case, as 

 at every step in the process of excavation, the height of the precipice, 

 the hardness of the materials at its base, and the quantity of fallen 

 matter to be removed, must have varied. At some' points it may have 

 receded much faster than at present, at others much slower, and it 

 would be scarcely possible to decide whether its average progress has 

 been more or less rapid than now." — Lyell. 



of course to a much more limited extent : by continual exposure to 

 the wearing action of water and weather a mass is undermined and 

 tumbles down, a portion of the debris is put in progressive motion 

 during every storm when the waves impinge otherwise than at right 

 angles to the shore line, and is moved, according to the locality, in a 

 certain prevailing direction, until meeting a projecting point or other 

 hindrance to its onward progress ; thus forming those shingle beaches 

 seen at many places on all rocky shores. 



The effects of the destructive action on banks of clay can be traced 

 wherever the shore is entirely of that material ; the owners of property 

 along many parts of Lake Ontario can bear testimony to its annual 

 encroachments; and, to come nearer home, many citizens of Toronto 

 must have witnessed the gradual alteration in the form and recession 

 of the clay banks between the old and new garrisons. 



The effects of the progressive action can also be witnessed at many 

 points on all the lakes ; but at none in a more remarkable degree than 

 at Toronto, although at other places to even a much greater extent. 

 And since to the peculiar motion of sand and gravel beaches will be 

 attributed not only the extraordinary changes the Peninsula is at pre- 

 sent undergoing, but even the greater part of the entire formation, it 

 will be necessary to explain fully the nature of it, and give the reasons 

 why the beach should have a tendency to move in one direction in pre- 

 ference to another. 



Let us take an example when the direction of the wind forms an 

 acute angle with the shore, a particle of sand resting on the surface is 

 driven forward up the inclined plane of the beach in the direction in 

 which the wave itself moves, the particle either remains at its now 

 elevated position or (as is more usual) sweeps along in a small curve 

 and rolls downwards with the expended wave to a new position, the 

 distance of which from the first will be in proportion to the mechanical 

 force of the wave and its direction ; another and each successive wave 

 drives the particle forward in a similar manner, unless by accident it 

 finds a resting place behind some obstruction or be buried by other 

 particles on the same mission as itself. If we take instead of a grain 

 of sand, a small pebble, we find that the same wave, or a wave having 

 the same force, moves it a less distance than it does the sand, that 

 larger pebbles being heavier make proportionately less progress, and 

 that stones still heavier are moved only when the waves have consider- 

 able power. All of these bodies, however, when within the impelling 

 force of the wave and placed in positions fairly exposed to its direct 

 action, seemed to be governed by the same law, and are moved forward 

 a less or greater distance according to their weight and gravity. 



Fig. 2. 



Xr-N 



-.X 



./'K.v = 'V»'' S '"'''' Y^'4.\ ■ 



The arrows denote the direction of the waves ; the dotted lines show the 

 paths of grains of sand and pebbles. 



The zig-zag direction taken by the sand and gravel on the beach is 

 indicated by the various dotted lines on Fig. 2, the smallest one is in- 

 tended to show the course of a grain of sand, and the two largest lines 

 that of pebbles varying in size. The progressive motion is slightly 

 suspended between each wave, but although intermittent is continued 

 so long as the seas break on the shore from the same quarter, and 

 until the moving mass meets with an obstruction, or bv reason of a 



