This is a hilly region; but what kind of a hilly region?just a tangle? I'd rather like it to be, but it's simpler in a way: a tableland six hundred or more feet high, into which valleys, small but sharp, are incised.
The tableland is a geological layer cake. The roughly level top is capped by a formation called Clay-With-Flints (laid down in the Eocene age), with a layer of chalk under it in the southwestern parts (Cretaceous age). The steep upper walls of the valleys are cut through a lower layer called the Upper Greensand (also Cretaceous). The lower sides and the bottoms of the valleys are cut through the Lower or Blue Lias (Jurassic). And at Uplyme the streams have dug into a yet deeper formation called the Rhaetic Beds (of the Triassic age), which also is the lowest layer in the sea cliffs.
These kinds of stone, especially the flints and the blue lias, appear among the local building materials.
Because of the relative toughness of these layers, a characteristic profile pervades the scenery. The top clay layer has been mostly planed away (the flints having settled through it). The Upper Greensand is quite hard, so it eroded slowly and forms the steepest slopes (it isn't as hard as sandstone or granite, so it doesn't form vertical cliffs like Monument Valley or the coasts of Cornwall). This steepest slope is often left to woods, or gorse or brambles, so that it looks even more distinct from the level fields above and the sloping fields below. The Blue Lias forms the somewhat gentler slopes, though at the bottom they tend to steepen again where the streams are entrenched. So the profile looks like this (exaggerated):
Once you start noticing it, you notice it often, with all the more pleasure for noticing its local differences. In the profile of Knoll Hill it shows simply. Where Springhead Road wrestles its way up, the top rampart is expressed and re-expressed, in several banks and bluffs at different angles, and in the peeling off of Rocombe Lane before the final climb, as if shirking it. A lane that goes around the semicircular head of a valley near Blackpool Corner is paralleled by a strip of woods on the steep arc below; a valley-collar.
The small valleys, which descend toward the broad Axe valley to
the northwest or toward the Char and Lim valleys to the southeast,
cut back into the plateau to various distances, as if trying to
meet (which they will do in a few thousand years, if the whole thing
has not been eaten away from the south by the sea). Thus this part
of the plateau is shaped something like a long leaf, scolloped deeply
on both sides, and the level pathway along the middle is sometimes
quite narrow. But once you get up onto it, you can ride just about
level, from Rousdon at the southwest end near the sea, to Lambert's
Castle at the northeast end.
But having laboured on bicycle up one of the steep-and-then-steeper lanes to gain the plateau, don't expect the plateau to be as flat as a floodplain. "I thought you said it would be flat up here!" It undulates and is rounded down toward its edges.