SIR J. HALL. PEBBLES AND SCRATCHES NEAR EDINBURGH. 203 
been long subjected to attrition in water; and I also observed, that 
many of them presented their principal or most projecting angle 
towards the west, and sometimes towards the north-west; which, ac¬ 
cording to my opinion, strongly implies the direction of the current 
which left them in the position in which they now rest. It is not 
the object of this paper to dip into the causes of these phenomena; 
but that such currents, as were capable of the effects which I 
have endeavoured to describe, have overflowed the surface of our 
globe, is to me clearly evident; and these scratches and grooves 
here mentioned are some of the minor, but clear proofs of its 
action.” 
In a very able and ingenious paper by Sir James Hall, in vol. vii. 
of the Transactions of the Koyal Society of Edinburgh, he has 
recorded his discovery of similar traces of the action of a mighty 
current on the surface of the hills and valleys near that city. These 
districts are not only strewed over with the gravelly wreck of rocks 
that have been drifted to a great distance from their native bed by 
the force of violent waters; but Sir James has also observed channels 
and furrows, which he calls dressings, still remaining on the surface 
of the hard rocks over which these waters passed, driving before 
them blocks and fragments of every substance that lay in the line of 
their course, and also excavating deep valleys. Where a mass of 
rock has been followed underground to where its surface has been 
protected by a covering of clay, it is found to resemble a wet road 
along which a number of heavy and irregular bodies have been 
recently dragged ; indicating that every block that passed had left 
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