80 W. A. E. Ussher — Historical Geology of Cornwall. 



the Isle of Wight to the appellation of Ictis on the ground of the 

 accuracy of that historian's descriptions. Jf the name Vectis 1 applied 

 exclusively to the Isle of Wight, Pliny's mention of it as lying 

 between Ireland and Britain would prevent one from putting too 

 much faith in the latitudes and longitudes of ancient geographers. 

 (Vide Note B.) 



To revert to more recent records. As the description of St. 

 Michael's Mount in the Domesday Book is so indefinite, and, from 

 the nature of the record, rather applicable to the lands belonging 

 thereto than to the geographical position of the Mount itself, there 

 appears to be little reason why the eight carucates mentioned in the 

 passage should not be regarded as arable lands on the adjacent 

 mainland belonging to the monastery. The submergence of the 

 Mounts Bay forest seems to have occurred considerably anterior to 

 any inundation on record, for the following reasons. 



First, — Mr. Came 2 mentions the extension of the old forest ground 

 seaward, traced to a depth of from twenty to thirty feet below spring- 

 tide level. 



Secondly, — There is every reason to conclude, with Mr. Carne, that 

 the forest bed met with in a pit at Huel Darlington mine, under 

 12 feet of marine sediment, four feet of peat, and eight feet of river 

 wash, is continuous with the forest bed on the beach. 



Thirdly, — Whilst the entombment of the forests in marine sedi- 

 ments indicates subsiding movements, the peat and overlying gravel in 

 Marazion Marsh, and the present positions of rock platforms slightly 

 higher than spring-tide at high-water, and of estuarine deposits, 

 seem to point to a slight subsequent elevation, not yet counteracted. 

 The changes which took place after the submersion of the old forest 

 ground can hardly have been comprised in eight centuries, and were 

 more probably operating during a period of more than 2000 years. 

 A belief in the pre-historic 3 submergence of the Mounts Bay forest 

 is by no means contrary to the identification of St. Michael's Mount 

 with the Ictis of Diodorus ; for, although the land may have been 

 at a slightly lower level in the time of Diodorus than at present, 

 the rapid disappearance of thirty-six acres of pasturage from the 

 West Green sand-banks 4 since Charles the Second's time, mentioned 

 by Dr. Boase (T.R.G.S. Corn. vol. iii. p. 131), leaves one free to infer 

 that prior to that time the bank was of still greater extent, so that 

 its eastward portion may have facilitated the passage to the Mount 

 by affording a ridge or causeway of sand covering the rocky isthmus 

 and passable in most conditions of the tides. The Wolf Bock and 

 the Seven Stones can scarcely be regarded as possible competitors for 

 the Ictis of Diodorus ; their admission would entail a subsidence of 

 at least 200 feet within 2000 years, as the former is seven miles to 

 the south-west of Guethenbras Point (Land's End district), with 



1 (Peacock, p. 183.) Pliny, Nat. Hist. lib. iv. § 30: "Sunt autem xl Orcades 

 modicis inter se discretae spatiis. Septem Acmodae, et xxx Hebrides ; et inter 

 Hiberniam ac Britanniam, Mona, Monapia, Eicina, Vectis," etc. 



2 T. R. G. S. Corn. vol. yi. p. 230, etc. 3 As far as Britain is concerned. 

 4 The banks are now only two or three acres in extent. 



