The great variety of the formation coming to the surface in the area under consideration has given a striking variety to the character of the landscape: the chalk downs of the North and centre, with their rounded outlines; the abrupt escarpments of the greensand in the neighbourhood of Shaftesbury; the rich grazing land of Blackmore Vale on the Oxford clay; and the great Heath (Mr. Hardy’s Egdon) stretching from near Dorchester out to the east across Woolwich, Reading, and Bagshot beds, with their layers of gravel, sand, and clay. The chalk heights are destitute of water; the streams and rivers are those of the level valleys and plains of Oolitic clays—hence they are slow and shallow, and are not navigable, even by small craft, far from their mouths. The only sides from which in early days invaders were likely to come were the south and east; and both of these boundaries were well protected by natural defences, the former by its wall of cliffs and the deadly line of the Chesil beach. The only opening in the wall was Poole Harbour, a land-locked bay, across which small craft might indeed be rowed, but whose shores were no doubt a swamp entangled by vegetation. Swanage Bay and Lulworth Cove could have been easily defended. Weymouth Bay was the most vulnerable point. Dense forests protected the eastern boundary. These natural defences had a marked effect, as we shall see, on the history of the people. Dorset for many centuries was an isolated district, and is so to a certain extent now, though great changes have taken place during the last fifty or sixty years, due to the two railways that carry passengers from the East to Weymouth and the one that brings them from the North to Poole and on to Bournemouth. This isolation has conduced to the survival not only of old modes of speech, but also of old customs, modes of thought, and superstitions. It may be well, before speaking of this history, to state that the county with which this volume deals should always be spoken of as “Dorset,” never as “Dorsetshire”; for in no sense of the word is Dorset a shire, as will be explained further on.