440 TROPICAL NATURE 



than twenty feet of frozen gravel and earth capped by a foot 

 of turf. This being near the shores of the Arctic Sea may 

 be a comparatively recent beach -formation and of no very 

 great antiquity ; but the remaining discovery was more im- 

 portant. Mr. W. J. M'Gee, a gentleman who has specially 

 studied the Glacial and post-Glacial formations for the U.S. 

 Geological Survey, described the finding by himself of a spear- 

 head in the quaternary deposits of the Walker River Canon, 

 Nevada. These beds consist of several feet of silt and loose 

 material at the top, then a layer of calcareous tufa lying upon 

 twenty to thirty feet of white marl, containing remains of 

 extinct mammalia, and resting unconformably upon somewhat 

 similar beds of earlier date. The spear-head was found with 

 its point just projecting from the face of the marl about 

 twenty-six feet below the surface. Before removing the im- 

 plement, he carefully studied the whole surroundings, and 

 finally came to the conclusion that it had been embedded in 

 the marl during its formation. The beds were deposited by 

 the ancient Lake Lahonton. They have been thoroughly in- 

 vestigated by able geologists, and have been referred to the 

 close of the Glacial period, or about the same time as the 

 hearth described by Mr. Gilbert. The spear -head is three 

 and a half inches in length, finely made, and well preserved. 



About a hundred miles north-west of St. Paul, in Central 

 Minnesota, a thin deposit has been discovered containing 

 numerous quartzite implements. They occur at a depth of 

 from twelve to fifteen feet in an old river terrace of modified 

 drift, and the deposit marks an ancient land surface on which 

 the implements are found, and which must have been de- 

 posited at about the close of the last Glacial epoch. 1 Mr. N. 

 H. Winchell, State geologist of Minnesota, has found similar 

 chips and implements in the upper part of the same deposit ; 

 and also human bones in the eastern terrace bluffs at Minne- 

 apolis, in a formation of about the same age as the above. 



The same writer reports a still more remarkable discovery 

 of a fragment of a human lower jaw in the red clay and 

 boulder drift, but resting immediately on the limestone rock. 

 This red clay belongs to the first or oldest Glacial period, and 



1 "Vestiges of Glacial Man in Minnesota," by F. E. Babbitt, Proc. of Am. 

 Assoc., vol. xxxii. 1883. 



