12 -—«S THE INSULATION OF ST. MICHAEL’S MOUNT. 
had this submerged forest as its primary basis; but if it can be 
shown that the tradition is older than any knowledge of the forest, 
the fact will in no way detract from the value of the latter as 
evidence. 
II. It is but fair to state that, Professor Max Miller makes 
no pretensions to geology, and that he does “not venture to 
touch the geological arguments.”* It is not surprising therefore 
that the question he puts to Geologists, as such,—‘‘ May not the 
Mount have always been that kind of halfisland which it certainly 
was 2,000 years ago ?”—must be met with a clear and an unquali- 
fied “No.” In order to a full appreciation of the grounds on 
which this answer rests, it will be necessary to give here a some- 
what detailed account of the geology and geography of the Mount. 
It is well known that the Mount is an island at every 
high water, and, with rare exceptions, a peninsula at every low 
water. Its distance from Marazion cliff—the nearest point of the 
mainland—to spring-tide high-water mark on its own strand is 
1,680 feet, as Col. Sir Henry James kindly informs me. The tidal 
isthmus consists of the outcrop of highly inclined Devonian slate 
and associated rocks, and, in most cases, is covered with a thin 
layer of gravel or sand. At spring tides, in still weather, it 
is at high water twelve feet below, and at low water six feet 
above, the sea-level. In fine weather it is dry from four to five 
hours every tide ; but occasionally, during very stormy weather 
and neap tides, it is impossible to cross for two or three days 
together. The Mount is an isolated mass of granite, measuring 
at its base about five furlongs in perimeter, as I am obligingly in- 
formed by Mr. J. P. St. Aubyn; and rising to the height of 195 
feet above mean tide, according to Sir H. De la Beche.t At high 
water it plunges abruptly into the sea, except on the northern or 
landward side, where the granite comes into contact with the slate, 
into which it sends veins and dykes, as may be well seen on each 
side of the harbour. Here there is a small plain occupied by 
a village, adjacent to which is the harbour, built in 1726-7, and, 
as Mr. Johns, the harbour master, has been so good as to write 
me, capable of receiving ships of 500 tons burthen. 
* p. 356. 
+ See Report on the Geology of Cornwall, &c., p. 15, 1839. 
