A HISTORY OF NORFOLK further slips. The beach deposits are nowhere very thick below the cliffs, and at various places they are now and again cleared off after heavy gales in some places and heaped up in others. The old church of Eccles-next-the-Sea, rendered famous by the descriptions of Lyell, must originally have been built in an alluvial valley separated from the sea ; it gradually lost the protection of higher ground, and was in 1839 surrounded by blown sand. Since that date the blown sand shifted inland and the round church tower for many years stood lonely on the foreshore several yards from high- water mark. In January, 1895, the tower was destroyed during a violent storm. CONCLUSION These evidences of destruction in one place and of accumulation in another are but continuations of geological history which tells of constant change. The strata of which we have evidence in Norfolk present to us all conditions from that of deep sea to shallow sea, and all climates from that of tropical to arctic. The present inland features are due mainly to the influence of rain and rivers subsequent to the great Ice Age. The melting of the ice which formed the Chalky Boulder Clay doubtless produced torrential streams which marked out some of the main lines of drainage, and the ordinary action of rivers carried on the work during the succeeding milder epoch which links on to the present. The land stood higher and extended much further, and the rivers had longer courses and greater falls. The passing away of the icy conditions left a great plain whose surface was formed partly of gravel and sand, partly of loam and Boulder Clay, and partly of Chalk and older strata. On such a varied platform the action of subaerial forces would vary, as rain sinks into porous strata, but directly erodes impervious deposits like clay. Beneath sheets of gravel overlying clay, the waters collect and issue where they can along the valleys. Subterranean watercourses no doubt exist beneath sheets of sand and gravel, as is evident from the permanency of certain springs. They flow along definite courses marked out on the floor of clay and must cause some subterranean erosion. Their courses may be indicated by slight sinking of the ground, and eventually patches and outliers of gravel become separated from the main mass. In this way may we account for some of the many gravel hills scattered over the clayey and marly regions, as near Holt. Evidence of man's existence during the formation of some of the earlier valley-deposits has been proved by the occurrence of Paleolithic implements. Many and great changes have taken place since then ; and we can only surmise that the present features had been mainly formed when his Neolithic and other pre-historic successors occupied the country. In some counties where there are broad alternate bands of impervious 28
