GEOLOGY. 233 



of the Alps, in the Black Forest, the Vosges as well as 

 the British Islands, in Scotland, Wales, and Ireland, I have 

 everywhere satisfied myself that the more extensive the glaciated 

 areas, indicated by polished surfaces and moraines in. any given 

 locality, the older they are when compared with glacial phenom- 

 ena circumscribed within narrower limits. It therefore follows, 

 from the facts enumerated above, as well as from a general con- 

 sideration of the subject, that the local glaciers of the White 

 Mountains are of more recent date than the great ice-sheet which 

 fashioned the t} r pical drifts. On another occasion I hope to show 

 that the action of the local glaciers of the White Mountains began 

 to be circumscribed within the areas they have covered, after the 

 typical drift had, in consequence of the melting of the northern 

 ice-sheet, been laid bare in the Middle States, in Massachusetts 

 and Connecticut, after even the southern portions of Vermont, 

 New Hampshire, and Maine had been freed, and when the White 

 Mountains, the Adirondacks, and the Katahdiu range were the 

 only ice-clad peaks in this part of the continent. 



"When in their turn the glaciers of the White Mountain region 

 began to melt away, the freshets occasioned by the sudden large 

 accumulation of water remodeled many of these moraines and 

 carried off the minute materials they contained, to deposit them 

 lower down in the shape of river terraces. I have recently satis- 

 fied myself, by a careful examination, that all the river terraces of 

 the Connecticut River valley and its tributaries, as well as those 

 of the Merrimac and its tributaries, are deposits formed by the 

 floods descending from the melting glaciers. What President 

 Hitchcock has described as sea-beaches and ocean-bottoms near 

 the White Mountain and Franconia Notches, as well as in the 

 Connecticut River valley and along the Merrimac, have all the 

 same origin. The ocean never was in contact with these depos- 

 its, which nowhere contain any trace of marine organic remains." 



IRON SAND ORES. 



In a paper before the American Association for the Advance- 

 ment of Science, Dr. T. Sterry Hunt said the presence of black iron 

 sand upon many sea-beaches has long been noticed both in 

 Europe and America. Their origin is to be found in the crystal- 

 line rocks, from the disintegration of which these sands have 

 been derived. The action of the waves, by virtue of the greater 

 specific gravity of these sands, effects a process of concentration, 

 so that considerable layers of nearly pure black sand are often 

 found on shores exposed to wind and tide. These black sands 

 vary in composition according to the localities, but as found on the 

 coast of New England and the Gulf of St. Lawrence consist of 

 magnetic oxide of iron, with a large admixture of titanic iron 

 ore, and more or less garnet, the purest specimens holding from 

 30 to 50 per cent, of magnetic grains. Such sands have long been 

 employed as sources of iron in India, in small furnaces where they 

 are directly converted into malleable iron. Early in the last cen- 



20* 



