14 WALKS AND TALKS. 



to be called a " pebble," and just where it is too large to be a 

 cobble-stone. Pebbles differ from them only in size. Pebbles 

 are hard and rounded, and seem formed of the same kinds of 

 rocks ; and the large, rounded, loose stones, which lie scattered 

 over the earth's surface, are in every respect only a larger 

 style of cobble-stones. It is plain that these are all one class 

 of rocks. So it has been decided ; and geologists call them 

 bowlders. This is an old name used by common people before 

 the science of geology existed, because these stones are rounded 

 like balls or boUs; and, being loose on the surface, are apt to 

 be bowled about. Even grains of gravel and sand appear to 

 be of the same nature as bowlders. You will also notice, 

 especially, that these rocks are all separate and detached, as 

 well as rounded, and they are of various colors and mix- 

 tures of colors. They are apparently different kinds of 

 rocks, which by some means have been brought promiscuously 

 together. Ledges of rock, which you must have noticed many 

 times, are generally all one kind of rock. They extend long 

 distances, and continue under the earth. Should a ledge of 

 rocks become broken up, and the fragments, large and small, 

 have their angles rounded off, and the whole then be scattered 

 over a township, far from the ledge, the result would be much 

 like what we see in our actual bowlders. From all we know 

 of rocks we are constrained to believe that our bowlders are 

 rounded fragments of broken up ledges. But where are the 

 ledges? Not in the next township or county. Perhaps not in 

 the next state or province. They have strayed far away from 

 their native ledges. They are " lost rocks." Now, it would 

 be very interesting to know where the parent ledges are ; and 

 it is curious how these fragments have been transported so far, 

 and how they became so rounded, instead of remaining angu- 

 lar, like the stones blasted from a quarry. 



Indeed, the more we think about this, the more astonishing 

 the facts appear ; for we call to mind that just such bowlders 

 are scattered all over our northern states, and they lie buried 

 beneath the surface in countless numbers. And the very sand 

 and gravel, to the depth of many feet, is only the same kind 



