SHAPES OF DRIFT FRAGMENTS. 23 



rounded bowlders of weathering can be seen on the southern brow of 

 Russell Mountain, in the town of Blanchard, Maine. 



Weather-carved forms. — Wlicu tho compositiou Or structuro of a rock is not 

 uniform, the weathering may proceed in some directions more rapidly than 

 in others. The longer such a rock is exposed to the weather the more 

 irregidar its shape becomes. In this way curious depressions have fre- 

 quently been formed on granite or other crystalline and noufossiliferous 

 rocks, which have often been supposed to be the tracks of men or the lower 

 animals or of infernal beings. On the islands of Monhegan and Menana, 

 off the coast of Maine, are certain markings on the rocks which have been 

 described by archeologists as inscriptions. The rather shallow depressions 

 forming the so-called letters are formed along tliree systems of joints of the 

 rock. Not a "letter" could I find that had not a crack (often minute) in 

 the rock at the bottom of the depression. In numerous instances fractures 

 of the rock near by have depressions along them, but no cross fractures or 

 depressions to form letters. It is evident that weathering would proceed 

 most rapidly on each side of such cracks, and thus in time a depression 

 would be made along the line of fracture. The geological evidence is thus 

 conclusive that the markings may he simply freaks of weathering along the 

 fracture lines of the rocks, and that no human agency is needed to account 

 for them. Yet if these markings prove to be capable of decipherment, we 

 shall have to assume the existence of a race of men acute enough to take 

 advantage of natural fractures and to form letters along them. 



In the western part of Oxford County are many bowlders of a black 

 eruptive rock which often have very uncouth and uiuisual shapes. This is 

 due to unequal weathering of the stones. Wlien gathered and placed in 

 trains along the walks near the houses, they remind one of the purposed 

 Mdeousuess of heathen idols. 



Water-rolled forms. — Watcr has but Httlo ability to grind and polish rock by 

 its own impact and friction. It derives its great power immediately from 

 the solid matter which it is able to move. In rolling drift fragments it 

 acts in two ways — by concussion and by attrition. In the first case the 

 fragments are hurled against one another or against the solid rock, and 

 since the angles are most exposed to the blows and are also most easily 

 broken, the stones are reduced to the well-known rounded form of beach 

 pebbles. In the second case the fragments are pushed past one another, 



