46 Correspondence. 



tliat the Drift-beds are exposed in the railway-cutting at Fremington 

 Station, and at Baggy Point, where he had found a great many flint 

 weapons. He next discussed the origin of the Pebble-ridge of 

 Northam Burrows, which is a line of pebbles extending far along 

 the coast and serving as a natural breakwater ; he suggested several 

 theories to account for it, and stated his opinion that the source was 

 the bed of the sea, not far off the granite of Lundy Island, and that 

 it was not a work of the past only, for fresh material was still being 

 added to the ridge. The writer concluded by pointing out the vast 

 degradation that was taking place on the north-eastern side of the 

 Burrows, where there is no barrier to protect the cliffs, and said 

 that within the last few years many acres of land had been destroyed. 



coi^iaiEJSipoisrnDEisrciE. 



FEOST AND SEA F. EAIN AND EIVEES. 

 To tlie Editor of the Geological Magazine. 



Sir,— Some observers would have us believe '^that Eain and 

 Elvers have been the principal agents in forming the present features 

 of the land," while to me it would appear that they did the least 

 part of the work, if we are to judge by what we see going on at the 

 present day. 



Eain, by itself, appears to be a Preserver, not a Destroyer, for if we 

 go up on an uncultivated mountain, we find that rain has covered it 

 with a mantle of Peat, and to that it can only add, unless other 

 agencies come into force. This is well exemplified where a hill-side 

 has been cultivated. Man, while he cultivated it, acted as the de- 

 stroyer, and Eain only as a carrier to take away part of the soil that 

 man had rooted up. If man ceases to cultivate that mountain side, 

 Eain causes plants to grow, then to become BeisJc, and eventually 

 Bog, which latter, as long as only Eain acts on it, continues to in- 

 crease in thickness. Eain must have some foreign help to commit 

 destruction. Let the hot summer sun open cracks in that bog, or 

 cattle form deep tracks, or man cut trenches in it, and what are the 

 results ? Eain continues the work that a foreign agent has begun ; 

 but even then it cannot do much work unless Frost comes to its aid, 

 to expand the water that fills the cracks and small fissures* and 

 breaks off large and small pieces, which falling into the hands of its 

 carrier, Eain, are washed down off the mountain. 



It is the same with rocks. Examine a mountain formed of hard 

 compact rock, that rain has run over for ages, and you will find that 

 the Glacial striae are scarcely obliterated, because the sun and frost 

 could not act on it. On the other hand, examine a mountain com- 

 posed of jointed or cleaved rock, and what are the results? The 

 summer sun opens the minute fissures, the winter frosts expand the 

 moisture in them, and then, and not till then, rain has work to do in 

 carrying away the debris. 



