from deep water to tidal shallows. The shallow water in which the Cornbrash limestones were deposited was followed by marginally deeper water in which the Kellaway Beds were laid down. The Kellaway Beds are only visible in the banks of streams and rivers, and the brick pits at Chickerell and Rampisham, where the succeeding Oxford Clays were quarried. The Oxford Clays were deposited in much deeper water and cover the valley floors between Weymouth and the Blackmore Vale. They can also be seen in the cliffs at Tidmoor Point, Jordan Hill, and the previously mentioned brick pits at Chickerell. Poor exposure, coupled with a decline in the brick industry, has made detailed mapping of the clays difficult, and now relies heavily on trenches dug for services. These excavations have unearthed some impressive examples of Septarian nodules. The exposure of Nothe Grit, to the south of Weymouth, suggests a return to shallower water conditions and a more turbulent environment. In the following 4.5 million years, a cycle of lagoonal, tidal, and deep-water environments caused by a world-wide fluctuations in sea levels, deposited beds of sand, clay, and limestone across the entire county. The Corallian strata can be seen on the Weymouth anticline, between Abbotsbury and Osmington. It then disappears to emerge as a low escarpment between Mappowder and Cucklington on the Somerset border. Near the top of this formation is the Ringstead Waxy Clay, in which large delta-shaped oysters are found and at the top of the Corallian is the Ringstead Coral Bed. Benecliff grit, a soft sandstone containing large doggers, is well exposed at the headland, Bran Point. Once a reservoir, oil sometimes seeps from the cliff here, and an oily residue is present in the sands nearby. Kimmeridge Clay The varied rock types of the Corallian are superseded by the Kimmeridge clay, a bed of dark clays and shales up to 500 m thick. These deposits occurred in a deep marine environment, 38° north. Deposited in an oxygen-deficient environment, the Kimmeridge beds make up the major part of the Purbeck Monocline and the periphery of the Weymouth Anticline. They form a low-lying band running north to south through the Blackmore Vale, and underpin the strip of land between the isle of Portland and the mainland. The unusual iron-rich sediment near Abbotsbury was, in a departure from the norm, deposited in shallow iron-rich water and the pale bands throughout the