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412 feet

300 feet

RIVER TERRACES.

Section of the St John River Valley at Fredericton.

Section of the fluviatile gravel,
(3) down to Clay (6) on which it rests

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Formation of River Terraces.

275

rally received hypothesis that they may have been caused by ice damming back rivers during, or subsequent to, the Glacial epoch.

Indeed the facts admit of being taken in support of widely

a, The narrow portion where the ice jam took place.

b, The plateau of Fredericton, twelve to fourteen feet above the usual level of the river. c, Extent of the inundation.

different conclusions. I repeat, Ist, that the river terraces, of the St. John for example, were formed during the elevation of the carboniferous sandstone, and therefore might be preGlacial or not. 2nd. Sometimes a glacier, running down a

T 2

valley, runs straight across another; and when thaws take place, there would be a jamming and banking back of the waters, which would indicate levels of subsidence much like the terrace cliffs. 3rd. That the terraces indicate fitful oscillations of level is also a feasible hypothesis. Referring to the banking-back supposition; I before alluded to the fact that there are now and then jams of ice on the great rivers of a serious character, so as to inundate large tracts in the valleys, and add to the deposits. An instance of this description is shown on page 277. It occurred during a sudden freshet of 1831, when the ice broke up suddenly on the St. John. The result was an enormous piling up of huge icebergs at a portion of the river called "The Narrows," about two miles below Fredericton, causing the river to overflow its banks and inundate the flat on which the capital is built.

So sudden and simultaneous was the breaking up throughout the river's course on the above occasion, that vast islands of ice got stranded, or set on end like polar bergs, and rose even to the level of the housetops, so as to threaten the complete destruction of the city as they passed onwards, scraping and tearing up the banks, and carrying destruction to everything that opposed their irresistible movements.

Now we might easily believe that similar phenomena (of course on a very much grander scale), at the close of the Glacial epoch, would be equal towards the formation of the heaps of valley gravels observed throughout the river courses and drainage hollows; moreover, without perhaps doing any violence to facts, we might on this supposition explain the great mounds and ridges of sorted detritus seen in various situations. I conceive, therefore, if a higher elevation of the country is allowed, and the land-ice theory entertained, that, as far at least as the fluviatile, or rather stratified gravel and clay deposits of the inland valleys are concerned, there is an apparent solution of the difficulty in these modern examples.

Sequence of Winter Climate.

277

At all events, in speculating on the past we do well always to seek for any present conditions which, if even multiplied by twenty or more degrees of intensity, would in their ways account for the above accumulations. As applied to the climate of New Brunswick, it may be stated that the meteorological conditions of the central and northern portions are pretty regular in kind. The mean temperature of the year may be put down at 44° Fahrenheit, the extremes attaining rarely 30° below zero, and 98° in the shade. (See Appendix, page 307.) The prevailing winds in the winter are from the

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north, and in summer from south and west.

Snow averages

three feet for four months, and is deepest in the northern districts, which are said to owe their greater fertility to that circumstance. A thaw takes place with considerable regularity shortly after New Year's Day, and when this is not the case an unusally cold winter is certain to result, such as took place in 1867-8. The cause of this sudden rise of temperature is not apparent, unless the prevailing winds, being then from south and east, might indicate a deviation of the regular atmospheric currents of South America, the West Indies, or

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