202 VALLEYS EXCAVATED. SCRATCHES ON SURFACE OF ROCKS. 
of the district: those which I examined consisted mostly of rocks, 
generally deemed of the oldest formations, such as quartz, por¬ 
phyries, granites, &c.; the native beds of which are far distant to the 
north and west of that part of the country. 
“ The disappearance of the trap in some of the glens and 
narrow vales seems to have been produced by the attrition of 
heavy bodies, set in motion by a great force of writer in rapid 
movement. 
“ 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 considerable degree of polish; 
and this polish is almost always seen marked by long lineal scratches. 
In other places there appeared narrow grooves, apparently formed by 
the rapid movement of large masses of rock having swept along its 
surface. 
“ 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 detected some of these 
scratches. Upon the surface there were scattered immense masses of 
trap, which, from their apparent weight, seemed perfectly capable of 
forming these scratches and grooves above described, had they been 
put in motion and impelled along the surface. Upon examining 
some of these huge masses, I found their surfaces scratched and worn 
. in such a way as to prove sufficiently indicative to me, that they had 
