S6 



GEOLOGY OF THE CAMPSIE HILLS. 



In some of the glens and narrow vales, where 

 the trap had not entirely disappeared, I perceived 

 upon its surface strong indications and marks of 

 attrition. In some places the surface of the trap 

 was smooth, and had evidently received a consider- 

 able degree of polish ; and this polish is almost al- 

 ways seen marked by long lineal scratches. In other 

 places, there appeared narrow grooves, apparent- 

 ly formed by the rapid movejnent of large masses 

 of rock having been swept along its surface ; and 

 I remarked, that these striae or scratches, were 

 very generally, in a direction from west to east, 

 excepting where inequalities of the surface, and 

 sudden turns in vales had partially influenced the 

 course of the current. In the eastern part of the 

 district, there occurs a small elevated plain slightly 

 undulated. Here the surface of the trap, in some 

 places, had lost its covering of soil, and was left 

 bare for inspection. Upon this plain, I again de- 

 tected some of these scratches, which were, in this 

 situation, generally in a direction from west to 

 east, sometimes deviating a little towards the south- 

 west and north-east, and sometimes towards the 

 north- w^est and south-east ; but in taking the 

 average or medium of these directions, their ge- 

 neral and true course seemed to me to be from 

 west to east. Upon the surface there were scat- 

 tered immense masses of the trap, which, from 

 their apparent weight, seemed perfectly capable 



