406 ATLANTIC ESTUAR1NE TIDES 



ST JOHN RIVEU TIDES 



Our data here are all for mean springs of July and August, 

 being due to a study by A. Willmer Duff.* In putting these 

 data into the usual form, the time intervals have been taken 

 from Indiantown. Although the tides are of a good river type, 

 there is a unique feature in the tidal falls at the river's mouth. 

 The entrance to the Bay of Fundy at the city of St John is by an 

 estuary five miles wide in deep water. Spring-tide ranges at the 

 city are of 27 feet ; time of rise, 5 h. 40 in. ; fall, 6 h. 45 m. Back 

 of the city "the waters of the river, previously occupying a 

 channel remarkable for its extent and breadth, become abruptly 

 confined in a narrow gorge [which] has its immediate origin in 

 a band of pre-Cambrian rock crossing the stream obliquely and 

 forming a barrier, over which the waters of the river and of the 

 bay flow alternately. From the relative levels of the harbor and 

 river and the known rise of the tide, it would appear that the 

 inward fall over the barrier at the suspension bridge is from nine 

 to ten feet; but as this inward fall is wholly confined to the last 

 third of the flood-tide, attaining its maximum with the latter 

 and again rapidly receding, the interval during which the river 

 is effectively resisted is greatly limited, not exceeding three or 

 four hours out of every twelve. Notwithstanding the limitation, 

 however, the effect is so far to set back the stream as to produce, 

 except in time of freshet, an alternation of upward and down- 

 ward currents, accompanied by a corresponding change of level, 

 which is appreciable even at Fredericton, a distance of over 80 

 miles from the mouth, resulting at low water, in a rise and fall 

 of not less than 10 inches." f Four times in the twenty-four 

 hours there are ten-minute periods of level water,} and then 

 steamboats can safely pass.g At very high freshets in April and 

 May there is no inward fall, as the tide does not rise high enough. || 



There has been some discussion as to the propriety of calling 

 the oscillations that result in the St John river tides. Mr Duff's 

 investigation, however, seems decisive. The oscillations are 

 tidal in shape, period, and progression, and are visibly born of 

 the Fundy tides in the Narrows; they are therefore tides. The 

 distances in the table accompanying are from Indiantown, just 

 upstream from the Narrows ; the ranges in inches. 



* Bulletin of Nat. Hist, of New Brunswick, vol. xv, 1897. 



f L. W. Bailey, Roy. Soc. Can. Trans. 1882, p. 281. 



% J. W. Bailey, St John River, p. 135. 



§ Ward's Account of the River St John, p. 17. 



|| Lockwood's Nova Scotia, p. 97. 



