716 | GEOLOGY OF OHIO. 
BEARINGS OF GLACIER FURROWS. 
LOCALITY. ROOK. NUMBER OB} Byarrne. 
SERVATIONS. 
South Bass Island................. Limestone, Waterlime Group.| Many. S. 80° W. 
" intersecting series i a 1 S. 15° W 
IRGUIR WS ISBN OVC Lo ccndocija0 e00000080 400 o Corniferous “ 4 S. 78° W. 
Sandusky City, Erie Co......... f " ce 2 8. 80° W. 
Baliwille ieee seacess ste yonee re Waterlime “ 1 S. 65° W. 
Genoa, Ottawa Co........... 0.05 ct ry and 
Niagara Groups........... Waa 2 8. 65° W. 
West Sister Island................. Limestone, Waterlime Group.| Many. S. 80° W. 
‘§ intersecting series a tf rs 1 S. 
Sylvania, Lucas Co ............... i and Sandstone 
Corniferous Groups............ 5 S. 50° W. 
Monclova, Lucas Co.............. Limestone, Waterlime Group. 4 S. 62° W. 
Fish’s Quarry, Lucas Co........ o Corniferous “‘ 1 S. 55° W. 
Whitehouse, Lucas Co........... ‘f vs il S. 50° W. 
Near Defiance, Defiance Co...) Shale, Huron Group.............. aia S. W. 
Near Junction, Paulding Co...| Limestone, Corniferous Group 1 Ss. W. 
imag, wAlemsiCowisen canto a Waterlime  ‘ 3 S. 35° W. 
Middleport, Van Wert Co...... sf ie 2 2 S. 15° W. 
The glacial markings on West Sister Island, as shown by Mr. Gilbert, 
demonstrate that the motion of the ice was from east to west. In the 
Waterlime of which this island is composed are numerous balls of chert 
which have been exposed to the action of the glacier. We now find these 
projecting from the general surface much more strongly on their eastern 
than on their western sides, and from each a ridge or trail of limestone 
which they have protected from erosion runs off toward the south-west. 
Around the eastern base of each nodule is a deeply excavated furrow, 
which leads off on either side of the ridge just mentioned. Occasionally 
these flint nodules are cracked and battered, as they could hardly have 
been except by the action of bowlders, which, held by the ice, had come 
in contact with them. The exceeding fineness of the sculpture around 
these nodules, as well as in many of the longitudinal furrows, prove that 
the erosion was generally done, not by stones held in the ice, but rather by 
sand, which, frozen into the plastic ice, was capable of executing any sort 
of carving and modeling with the greatest accuracy. The glacial furrows 
on Kelly’s and Put-in-Bay Islands have been often referred to, and are 
more surprising for their magnitude, extent, and variety than any 
others known in the country. In the fossiliferous limestone of Kelly’s 
Island the glacial surface is thickly mottled with sections of corals and 
other fossils. These are ground down, often as nicely as they could be 
done by hand, and show distinctly that sand, under the ice, must have 
been the grinding agent. In many localities on these Islands the gla- 
cial furrows curve around any prominent point or rock mass which was 
