In the preparation of its Dorset inventory the Royal Commission on Historical Monuments (England) has drawn new attention to a remarkable earthwork which has long been known to exist on Bindon Hill, adjoining Lulworth Cove, Dorset. The significant topographical features are as follows. For many miles of Dorset coast the cove is the only natural harbour where in all weathers small craft may lie up with safety. In terms of human time, it must long have approximated to its present shape, the product of a fairly simple geological process. The successive strata hereabouts (from bottom to top) are Purbeck limestone, Wealden clay, and chalk; but they are all here uptilted towards the south through nearly 90 degrees so that in effect they lie side by side with the limestone as an outermost barrier against the sea. In ages past a chalk-stream wore a gap through the limestone down to sea-level, admitting the sea to the Wealden clay, which it then proceeded to scoop into a basin until stopped by the more solid chalk beyond. The tiny descendant of this incisive stream still flows unnoticed beside the road down to the harbour.