Scientific Intelligence. — Geology. 385 



my stick, and thrust it into the flame, which kindled the flax. Soon 

 after, the Jack-o'-lantern became extinct at a height of about two or 

 three feet above the stature of a man. It soon after reappeared of 

 smaller size (for I was led to believe that it was the same), on an- 

 other pool placed at a little distance. I ran immediately towards it, 

 but in vain, as it vanished in a few seconds. I saw no others that 

 night. The remains of the flax liad not that garlick-like smell pe- 

 culiar to phosphorus, but a faint peculiar odour which I cannot de- 

 fine, and which appeared to me to be rather of a sulphureous and am- 

 nioniacal nature.* 



GEOLOGY. 



5. Geological Chronometer. — The Athenawn gives an abstract of a 

 paper, read by Mr Lyell to the Geological Society, which affords some 

 data for guessing at the period when the Mastodon lived, the gigan- 

 tic quadruped whose bones are found in the .soil in various parts of 

 North America. Near Goat Island, which is close to the Falls of 

 Niagara, and at the Whirlpool, which is four miles further down, 

 Mr Lyell found a fluviatile deposit, 40 feet thick at the latter locality, 

 consisting of beds of sand, and containing many recent shells, with 

 remains of the Mastodon. When the deposit was formed by the 

 river, its waters must have been 300 feet higher than at present. 

 It follows, that the deep channel from the Whirlpool to Goat's 

 Island was then uncut, and that the Falls were below the Whirlpool. 

 Hence, it appears, that since the bones of the Mastodon were depo- 

 sited in these beds, the Falls have receded (according to maps in our 

 possession) four miles, and possibly much more, for when the depo- 

 sit was formed, the Falls may have been, not at the Whirlpool, but 

 some miles below it. According to an estimate made some years 

 ago, the Falls recede (by undermining the rock) about a yard per 

 annum, but Mr Lyell assigns a foot as the more probable amount ; 

 and as they have receded in this case four miles, or 20,000 feet, we 

 may infer that 20,000 years have elapsed since the bones were de- 

 posited in the fluviatile sediment, and since the animal lived. If the 

 estimated rate of recession is accurate, the time cannot be less than 

 this, bat it may he more. The result, though wanting precision, is 

 not without its value; and there is little doubt that by the aid of 

 such natural Chronometers as Niagara Falls, and other means, we 

 shall by and by be able to measure by centuries geological periods of 



* L'Institut, No. 471, 5th January 1843, p. C, 



