UgA PHILOSOPHICAL TRANSACTIONS. [aNNO 1717. 



afterwards the remaining part of the isthmus should in the space of 2000 years 

 and upwards, be worn away by the flux and reflux of the tide to 1 6 fathoms, 

 its present depth, is by no means incredible. 



As to the second point, viz. whether this isthmus was really worn away, or 

 not : and 1. That remarkable ridge of land, in the strait itself, shows that the 

 land there was formerly much higher, but being continually washed away by 

 the tides, for some thousands of years, was reduced to the state in which it is 

 at this day ; especially, if we consider, that it is a constant and infallible rule, 

 that the more the bottom of the sea is worn or washed by its waters, the more 

 level and even it becomes. 2. The steep white cliffs, consisting of chalk and 

 flint, on the opposite shores of the straits, and answering to each other for 

 miles on each side, plainly show that they were formerly separated by washing 

 away the intermediate earth. 3. The state and condition of that tract of land, 

 called Rumney- Marsh, agrees very well with the supposition of an isthmus : 

 for, while the isthmus remained, it must have been an obstacle to the tides; 

 and consequently have caused the overflowing of Rumney-Marsh, as being a 

 plain low bottom; and that this marsh was formerly sea, appears from its 

 strong bulwark, as also from the teeth and bones of a Hippopotamus, or some 

 other sea-animal, dug up at Chartham in lt)68, at 17 feet deep; Phil. Trans. 

 N° 272, 275. But an anchor, dug up thereabouts, shows it very evidently. 

 After the isthmus was broken through, and all obstacles removed, the sea re- 

 tired from Rumney-Marsh, into its channel; whence what was formerly an 

 aestuary, is now a fertile plain, 20 miles long and 8 broad, and yielding very 

 good pasture for cattle. 



Lastly, supposing, that there was formerly an isthmus here, it is very easy 

 to conceive how wolves, and other noxious animals, might come into Britain: 

 whereas on the contrary supposition it will be ridiculous to imagine, that they 

 were transported thither in ships, for the conservation of their species. 



Nor is it any objection, that no mention is made of the breaking through of 

 this isthmus in any histories, either by the Latins, Greeks, or any other nation: 

 for how modern is the date of history, compared with that of the world? from 

 the beginning down to the first history now extant, which is that of Herodo- 

 tus, there are about 3500 years, and from Noah's deluge 1800; but in such a 

 vast space of time, what conjunctions of causes might happen, and what 

 changes might thereby be produced in the earth, is not easy to determine. 

 Yet we must not allow that we have no hints of this event in history ; for what 

 is plainer than this passage in Virgil. 



Penitus toto divisos orbe Britannos. 



" Do not ye think (says the learned British Antiquary Jo. Twin de rebus 



