70 GEOLOGY OF OHIO. 



while Prof. Tyndall claims that^the change of form in ice is effected 1 

 by fracture and regelation ; ice having the peculiar property of reuniting 

 in a solid mass when fractured and the separated surfaces brought to- 

 gether again in water. It has been generally supposed that the position 

 taken by Prof. Tyndall had been demonstrated to be correct, but ice 

 sometimes exhibits a change of form where regelation seems impossible. 

 For example, Dr. Kane describes, in his Arctic explorations, a sheet of ice 

 eight feet thick, resting on supports twenty feet apart, which curved down- 

 ward five feet, although the mercury was constantly far below the freezing 

 point. This seems to be an experimentum cruris, and shows that ice is 

 capable of undergoing a change of form through a rearrangement of its 

 molecules without fracture and regelation. This 'will not seem surprising 

 when we reflect that most solids exhibit the same property in a greater 

 or less degree ; even iron and steel, which may be permanently bent 

 without fracture, show a change of form through a molecular rearrange- 

 ment. The motion of glaciers is undoubtedly effected partly by sliding, 

 partly by fracture, and in part also by a true plasticity or molecular 

 change of form in the ice which composes them. 



DRIFT GOLD. 



Gold has unquestionably been found in the Drift in a large number of 

 localities in Ohio and Indiana. My attention was first called to it many 

 years since by Prof. L. H. Smith, then of Kenyon College, who showed 

 Ine scales of gold taken from the Drift near Bellville, in Knox county. 

 Since the organization of the Geological Survey I have received a num- 

 ber of additional specimens obtained from the surface deposits in the. 

 same region. It occurs in very fine particles, and is associated with beds 

 of clay, sand, and gravel, of which the latter is largely composed of quartz 

 pebbles. These may have been derived from the Waverly conglomerate, 

 which has here been very extensively eroded. In the adjoining county 

 of Licking, Prof. Andrews reports finding gold in the Drift at several 

 points. He mentions that — 



" In the summer of 1868 gold dust of the value of seventeen dollars was washed 

 out of fine drift material, in a little gully, well up the hill-side, on the farm of Daniel 

 Drum, Bowling Green township, a mile north of Brownsville. The largest grains 

 were reported to be of the size of a wheat grain. * * Near Newark, and north of the 

 high grounds which divide the waters of the Licking river from those of the Moxa- 

 hala and its tributaries, are other and larger deposits of gold-bearing sands. The 

 place examined by me was one and a half miles south-east of Newark. Here is a 

 range of Drift terraces, about fifty feet above the bed of the Licking river. These 



