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 A HISTORY OF NORFOLK together with the seed that has been sown, the material being heaped against a neighbouring bank. The sands (sometimes termed ' Middle Glacial ') which underlie the main mass of Chalky Boulder Clay have been exposed on the coast south of Winterton. Here and further south in Suffolk they show comparatively little disturbance. They are false-bedded, they contain much coal-smut or comminuted fragments of lignite, and sometimes grains of chalk. At Caister, near Yarmouth, and again at Billockby and other places, many species of shells have been recorded by S. V. Wood, jun., and Mr. F. W. Harmer, who regarded them as belonging to the deposit, and to a comparatively mild Interglacial period. It is, however, much more probable that the bulk of the shells, which are worn and fragmentary, were derived from the Crag.* Pebble-beds are met with occasionally in the sands, as near Ched- grave, north of Loddon, Heckingham and Haddiscoe. Sometimes the sand is indurated. This happened at Mackie's Nursery, near Norwich, from the infiltration of water charged with carbonate of lime from the overlying Boulder Clay. The sand was cemented with the calcareous matter, and was in old times locally used as a building-stone. Occasionally we find coarse gravel under the Boulder Clay, as at Ashwell Thorpe, and also at Roydon, near Diss, where many derived Jurassic and other fossils have been found. This gravel may be regarded as a torrential deposit, formed by the melting during its earlier stages of the ice-sheet which formed the Chalky Boulder Clay. The gravels and sands yield water locally, upheld by the Lower Boulder Clay or by the loams of the Contorted Drift. At Holt copious springs are thrown out beneath the gravels and sands which form the plateau above the marly Contorted Drift. At Costessey, St. Walstan's Well was in old times a famous healing spring, and this issues from the Glacial sands. Many of the springs along the Cromer coast are ferruginous, their courses being marked by dark red stains on the cliff faces. A good deal of ochreous matter locally occurs in all the gravels of Norfolk, and the Rev. A. R. Abbott found slag in the hollows known as Weybourne Pits, which he attributed to early British workings for iron ore. Iron slag also occurs on Beeston Pleath, but Mr. C. Reid considered that the ore might possibly have been brought. Bog iron ore occurs in some of the valley gravels ; and it may be mentioned that iron-pan, a term applied to cemented layers of sand and gravel, is met with at various horizons and localities. Here and there beneath the Chalky Boulder Clay there are beds of finely laminated loam similar in character to those before noticed in the midst of the Lower Boulder Clay. Some of these masses are remarkably contorted, as may be seen near Diss railway-station. At Hedenham there was formerly a Roman kiln where the loam was worked. 18
 * See H. B. Woodward, ' Glacial Drifts of Norfolk,' Proc. Geol. Assoc, vol. ix. p. 113.