Page:A Short Account of the Botany of Poole.djvu/4

4 forming the northern and southern boundaries, converge, but do not entirely meet, until they arrive as far west as Dorchester, which is the extreme western point of the Isle of Wight basin. To the east, there is no other boundary than a general rise of surface; and even this does not exist immediately along the coast.

Thus, it appears that there is a large district left by the chalk, which, near Poole, is about fifteen miles in diameter. This is occupied by the plastic clay, the level of which, descending from the northern boundary before named, sinks at Poole, below the level of the sea, and rises again on the coast of Purbeck, forming the capacious haven known as Poole Harbour.

Large patches of clay and sand, as is usual in this formation, occur throughout this district, both varying much in colour. There are also large beds of gravel, some of them very extensive. It would be irrelevant here, to speak of the excellence of the clay from this trough, and it is too well known to render this necessary. The gravel is in some places extremely fine and bright, in fact, the best I have any where seen.

As it is not professed here to give a lengthened geological account, it is not necessary to expatiate farther on the subject, but to apply the remarks already made, to the Botany of the district.

It is evident then, that there is a great diversity of soil in the neighbourhood of Poole, and a very rich Flora may naturally be anticipated: when, however, all the peculiarities and modifying influences have been cited, still higher expectations will be raised, yet I feel confident that no one will be prepared for the very numerous catalogue, which this district affords; and those who have taken a