114 GLACIAL PHENOMENA IN MAINE. 
owe their origin to oscillations of the front end 
of a glacier, pushing forward a mass of loose 
materials, thus throwing it up into a trans¬ 
verse ridge, and then melting away to some 
point farther back. I have already shown, 
in previous articles, how such walls are con¬ 
structed, often forming concentric ridges one 
within another, each of which marks a retreat¬ 
ing step of the glacier. Sometimes the sum¬ 
mit of the horsebacks is so broad and even 
that the country people consider them as nat¬ 
ural roads, and build their highways along 
them. They are indeed occasionally so sym¬ 
metrical that they have been taken for artifi¬ 
cial Indian mounds. The most perfect one I 
have seen stretches through Lagrange town¬ 
ship, between Bangor and Mount Katalidin, 
its direction being mainly from north to south. 
Leaving the horsebacks and the open coun¬ 
try on the second day of our drive, we entered 
upon a more wooded region, which brought 
us through the townships of Lagrange and 
Brownville, to the Ebeeme Mountains, at the 
foot of which the Katalidin Iron Works are 
situated. This is not only a very picturesque 
spot, but a most interesting locality with refer- 
