BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 21, pp. 447-448, PLS. 32-34 AUGUST 10, 1910 



IN TEERUPTION IN THE FLOW OF THE FALLS OF NIAGARA 

 IN FEBRUARY, 1909 



BY J. W. SPENCER 



(Read before the Society December 29, 1909) 



CONTENTS 



Page 



Previous fluctuations 447 



Fluctuations of 1909 447 



Similar occurrences 448 



Previchjs Fluctuations 



Since the year 1890, the mean level of Lake Erie has fallen about 1 

 foot^ and the basin above Goat Island about a foot and a half. From that 

 year until the end of 1905, the mean annual fluctuations varied scarcely 

 more than 1 foot, while in one case the mean monthly variation reached 

 nearly 2 feet; but during the progress of storms, when the wind has 

 changed to the opposite direction, the fluctuations have been found to 

 reach 5 or even 6 feet. 



Fluctuations of 1909 



During January and the early part of February, 1909, the lake level 

 was below that of the mean, but on February 10 Lake Erie rose nearly 3 

 feet above the mean annual average height (1889-1905, inclusive), while 

 in the following and succeeding days it fell with a northerly wind to 4 

 feet below the mean (as shown by the records of the gauges as furnished 

 the U. S. Lake Survey). This was on February 14. At this time the 

 weather was very cold. On account of the reduced depth of the water on 

 the upper rapids, as the ice was forming, it remained anchored to the pro- 

 jecting rocks and was not carried over the falls; so that the New York 

 channel and the main channel to about 600 feet outside of Goat Island 

 were frozen over, except one small lead, which scarcely showed any current 

 where ordinarily it is a rushing torrent. It must be emphasized that the 

 ice was not an accumulation of blocks carried down from Lake Erie, as 

 often occurs, like in the jam of the following April. As the blizzard con- 



ij. W. Spencer: EvoUitlon of the Falls of Niagara. Geological Survey of Canada, 

 p. 190. 



(447) 



