308 On the Upheaval and Sinking of land, $*c. [No. 4. 



exactly similar to that with which our estuaries are being silted up. 

 In a great majority of cases the blue clay is filled with the roots of the 

 mangrove — a shrub which only grows within high water mark — avoid- 

 ing water of more than four or five feet deep. The fangs and fibres of 

 the roots are perfectly entire — some of the thickest of them, indeed, are 

 but imperfectly decayed, — most of them are converted into a substance 

 like peat ; and when dried break with a conchoidal fracture and semi- 

 resinous lustre something between jet and lignite. These roots and 

 this arrangment is found to prevail all around the Island of Bombay, on 

 many parts of the Island of Salsette, on the shores of the Gulf of Cam- 

 bay, and at Kurrachee in Scinde. This state of things is not peculiar 

 to creeks, bays, or estuaries ; and can in no way be accounted for by 

 the ponding back of water — it prevails all around the shores of our 

 islands and estuaries into the interior as far as the gravel or concrete 

 beds themselves, and is visible on those portions of our shores exposed 

 to the full force of the ocean. It seems very probable that the New 

 Holland trees described by Mr. Damier, and the Madeira Wood men- 

 tioned by Dr. Macaulay, may belong to the same class as the roots I 

 have described, though I have not felt warranted in adducing them as 

 proofs of the hypothesis. 



I am satisfied that to this variety of objects the lignite, found near 

 Cochin inlat. 8 D , belongs; and that, were our shores examined, it would 

 be found at intervals everywhere along them. In Scotland at Perth, in 

 the Carse of Gourie,* in the carses of Falkirk and Sterling, under the 

 present city of Glasgow, and along the banks of the Clyde, boats and 

 canoes have been dug out from under ten to twenty feet of alluvium, 

 and still ten or twenty feet above the level of high water. Mr. 

 Chambers infers from these things, and I think most conclusively, 

 that the habitation of our island took place before the last thirty or 

 forty feet of its elevation was gained from the ocean. May we not go 

 further than this : — from the relations of these relics of human art to 

 the peat beds and submerged forests around is it not probable that the 

 depression under review was in progress within the human period ? 



The absence of roots in situ is no proof of a depression never having 

 occurred : at the present moment, for every fifty yards we have man- 

 groves, we have at least 1000 where there are none ; and on abrupt, 

 * Chambers's Old Sea Margins, page 19. 



