468 



SCIENCE. 



species. In its subsequent appearance, hereafter, it may 

 now be recognized. 



The Crambida? are small moths with narrow front 

 wings, often marked with metallic spots and lines, which 

 are frequently driven up for short staccato flights in our 

 pastures and meadows during the fall months. 



The paper concluded with a resume of the history of 

 the species, so far as known at present, which is omitted 

 as not of general interest. 



CANONS— THEIR CHARACTER AND ORIGIN* 

 By Hon. William Bross. 



To the professional geologist it may seem an imper- 

 tinence for a layman to offer any opinions as to the 

 character and the origin of canons. He may ; however, 

 it is hoped, use his eyes without offense, and form such 

 conclusions as the facts which he has observed, may 

 appear to warrant. If they should not agree with the 

 recognized principles of the science as now understood, 

 he will be no worse off than scores of learned Professors 

 in the past, for in this, as in almost every other science, 

 nearly every conceivable absurdity was exhausted before 

 theories were made to agree with acknowledged facts. 

 And here, at the commencement, the conclusion to which 

 the observations to be presented somewhat in detail have 

 led, may as well be stated — viz.: that canons were formed 

 by some great convulsion of the earth's surface, or by 

 the contraction of mountain chains from their igneous 

 condition in the early history of the planet. Take, for 

 instance, the canon of the Saguenay — a vast fissure in 

 the mountain chain that lies on the north side of and 

 nearly parallel with the St. Lawrence. The fissure or 

 canon is some fifty or sixty miles long and lies nearly at 

 right angles to the river. Something like a mile apart, 

 the perpendicular rocks on the north side are, at some 

 points, about 1,500 feet high, the water at their base 

 being several hundred teet deep. No man in his senses, 

 it seems to me, could possibly conceive that this gorge 

 through the granite mountain could have been formed by 

 the action of the insignificant river that empties into Ha- 

 Ha Bay at the northern end of the canon. The surface 

 of the water, for the whole distance of sixty miles, is on a 

 level with the St. Lawrence, in some places it is several 

 hundred feet deep and the canon is about a mile wide, 

 through the solid granite rocks. And here another 

 general principle may as well be stated, that, with a 

 single exception, the width of this and the other canons 

 hereafter to be noticed, is scarcely ever more than a 

 fraction of a mile; seldom a single mile — a fact that 

 strongly indicates uniformity in their origin. And be- 

 sides, the mountains on both sides are generally nearly 

 of the same height. 



TAKE THE CANON OF THE HUDSON, 



where it passes through the Blue Ridge, above and below 

 West Point. The channel is deep, the tide ebbing and 

 flowing far upwards towards Albany ; the mountains on 

 both sides, though rounded off towards their summits, 

 doubtless during the glacier period, are about of the 

 same height, and there is a general correspondence in the 

 dip and thickness of the vast strata of rocks on both sides 

 ot the river. With the exception that the canon is far 

 above tide water, the same general facts are witnessed 

 in that of the Delaware at the water-gap through the 

 same spur of the Allegheny Mountains. In this case 

 there are two well-defined ledges corresponding with 

 each other on both sides of the river ; the water is deep 

 and sluggish while passing through the gorge, and all 

 the facts seem to point, with unerring certainty, to some 

 great convulsion in Nature as the origin of the canon. 

 With the exception that the current of the Potomac is 

 swift at Harper's Ferry, the break in the mountain there ( 



* Head before the A. A. A. S., Cincinnati, 1881, 



so graphically described by Jefferson, is very similar to 

 that of the Delaware. This gorge may not have been 

 relatively as deep at its formation as those of the Hudson 

 and the Delaware. 



THE CANON OF THE NIAGARA 



was confessedly formed by the action of the river; but, 

 if the structure of the rocks forming the canon between 

 the falls and Lewistown be considered, the exception in 

 this case, it is believed, will prove the rule enunciated at 

 the beginning of this paper. The rocks underlying the 

 country between Lewistown and Buffalo are nearly hori- 

 zontal, and are, in round numbers, as indicated by the 

 gorge below the fails, some 200 feet thick. The upper 

 strata, for say half the distance, are solid limestone, un- 

 derlaid for perhaps an unknown depth, by soft sandstone, 

 scooped out with comparative ease by the great cataract. 

 Hence, the support of the upper stratum ot lime-rock is 

 gradually worn away, and it falls into the gult below. 

 On the American side of Goat Island, where only a frac- 

 tion of the river falls over the precipice, the lime-rock lies 

 below in vast blocks, and a rapid is gradually forming, 

 while on the Canada side, the immense river scoops out 

 the sand-rock to a great depth, and the falling sections 

 of the lime-rock are buried out of sight forever. Below 

 the railway bridge, for a long distance, there is a terrible 

 rapid, showing that some other rock at the bottom of the 

 river was harder than the sandstone, or that the stream 

 is partially damned up by the lime-rocks thrown down 

 between the bridge and the present fall, forced to the 

 position they now occupy by the water, debris, and ice 

 pressing clown from above as the river gradually receded 

 towards Lake Erie. This recession will doubtless con- 

 tinue even back to Lake Erie, unless the sandstone dips 

 deeper down into the earth, and the limestone strata be- 

 come thicker or some other hard rock fills the entire face 

 of the cataract. Then the fall would gradually wear 

 away at the top and become a rapid of gigantic propor- 

 tions. Now, if the Niagara River, with its vast volume 

 of water at first falling over a lime-rock ledge, at Lewis- 

 town, underlaid by a friable sandstone base — a condition 

 of things found, it is believed, in no other canon upon the 

 continent — has required untold ages to work its way up 

 to its present location, how is it possible for the compar- 

 atively small rivers heretofore named, and those to fol- 

 low, to wear away a pathway to the sea through great 

 mountain ledges of the hardest rock ? Such a conclusion 

 would be absurd. 



THE CANON OF THE MISSISSIPPI 



extending, say from Dubuque to the head of Lake Pepin, 

 some 200 miles or more, is an exception to the rule above 

 proposed, mainly in its width, which is some five to seven 

 miles. The sandstone bluffs on either side are generally 

 perpendicular from the top downwards from 200 to 300 

 feet, when the debris slopes down to the bottom lands 

 or to the majestic river as it sweeps through the alluvium 

 from one side of this broad canon to the other. There 

 are doubtless good reasons for the opinion that the 

 waters which now find their way from Lake Winnipeg to 

 Hudson's Bay once flowed south and filled full the broad 

 space between the beautiful bluffs of the Upper Mis- 

 sissippi. 



THE GORGE OF THE UPPER MISSOURI, 



situated about loo miles below Fort Fenton, is one of 

 the most marked, as it is one of the most beautiful, can- 

 ons on the continent. The walls are perpendicular, of 

 white sandstone, scarcely a mile apart, and some eighty 

 feet high. On the top of these walls there is a layer of 

 clay, perhaps of the same thickness, rounded off grace- 

 fully by the winds and storms, while in some places it 

 has been all worn away, and the tops of the white 

 sandstone ledges appear as castellated forms, reminding 

 one of the Milan Cathedral, or some of the old ruins 



