NATURE NOTES. 283 
On the west side of the cliff, close to the brick wall near 
the edge of the loch, malachite occurs in thin films, and in 
very small radiating crystals, associated with pseudomorphs of 
limonite and hematite after pyrites. The malachite results 
from the oxidation of copper pyrites (chalcopyrites), and is 
scattered through small vertical veins in a matrix of cale spar 
and quartz. 
The writer estimated the amount of copper per ton of 
ore, the result of the estimations being, in round numbers, 
40 ounces and 36 ounces respectively, in each of two assays. 
A little of the copper was reduced to the metallic state and 
purified, as a specimen of copper from Arthur's Seat. 
R. DYKES 
THE BODETHAL IN THE UNTERHARZ—EROSION OF VALLEYS 
BY RivER ACTION. 
It is a truism nowadays to state that the most stupendous 
results in Nature have been caused by very slow and almost 
silent methods—a fact in nowise detracting from the 
majesty of continuous and all-pervading creation, but rather 
enchancing its grandeur. This is strikingly exemplified in 
the case of erosion by rivers or streams of valleys, glens, and 
ravines, names applied according to the varying breadth or 
narrowness of the eroded parts. The theory that the main 
course of rivers has been primarily decided by sea-action 
does not, in the least, lessen our wonder at the enormous 
excavating power they possess, especially if they flow over a 
rocky surface. We need only walk to the top of Blackford 
Hill to see what has been accomplished in that way by the 
little Braid Burn. The finest instance that has come under 
my own observation is that of the Bode Valley, rightly 
called “ The Crown of the Harz.” The Bode stream has 
eaten its way through the hardest rocks, and, although 
beautiful during its whole course, the climax is reached at 
the great rock chasm, where rise on one hand the gigantic 
_ granite mass of the Rosstrappe, and on the other the 
