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 A HISTORY OF SUFFOLK be found beneath the alluvium of Mildenhall Fen, and perhaps for some distance beneath the levels west of Lakenheath. The base of the Lower Chalk has nowhere been exposed in the county, and indeed only the higher portions of the grey Chalk marl, which is reckoned to be 60 or 70 feet in thickness, outcrop in the north- west. This marl is surmounted by the Totternhoe Stone, which com- prises about I 2 feet of grey gritty limestone, largely made up of commi- nuted fragments of Inoceratnus and containing green-coated phosphatic nodules at the base. The beds have been worked for freestone at Isle- ham, and they probably outcrop to the north-west of West Row. At this locality a band of light red chalk was observed by Mr. Jukes-Browne in the grey chalk which occurs above the Totternhoe Stone.' This higher portion of the Lower Chalk consists for the most part of grey and white blocky chalk or clunch, about 80 feet in thickness, with at top a layer 3 or 4 feet thick of yellow shaly marl and hard chalk, char- acterized by Actinocamax plenus. These beds extend from West Row eastwards to near Mildenhall, Eriswell and Lakenheath.^ The Middle Chalk comprises at its base the Melbourn Rock, a hard sandy nodular layer about 8 feet thick, named from Melbourn in Cambridgeshire. It has been observed near Worlington. The overlying yellowish and somewhat nodular chalk yields Rhynchonelia cuvieri, Inoceramus mytiloides and Galerites siibrotundus. The beds are exposed in pits east of Mildenhall, to the east and north of Eriswell and to the north-east of Lakenheath.^ The higher portion of the Middle Chalk, characterized by Tere- bratulina, consists of softer white chalk with layers of marl and nodules of flint ; and it extends from Newmarket, east of Mildenhall, to the neighbourhood of Brandon, a region where the Chalk is much hidden by drift sand. Only in the neighbourhood of Newmarket does the Chalk present its characteristic features of open downs with short, springy turf, such as we find over the well-known training grounds and racecourse.* Northwards to Mildenhall and Thetford, owing partly ' to the cappings of Drift as well as to the amount of sand that seems to have been blown over the Chalk, the usual features of a chalk-tract are almost absent. We have no sharp escarpment, no deep valleys, and the flood of sand has given rise, in places, to barren heath-land.' Large plantations of fir and larch have been made, elsewhere much of the ground is ' little else than a gigantic rabbit warren,' although rye, barley and potatoes are grown in places. ° In this region, as might be expected, there is a scarcity of surface water. 1 Geol. Mag. (1887), p. 24. ^ Whitaker and Jukes-Browne, ^arl. Joum. Geol. Soc. xliii. 547, 554; Whitaker and others, 'Geology of South-western Norfolk,' etc., Geol. Survey (1893), p. 29. ^ Jukes-Browne and Hill, ^arl. Journ. Geol. Soc. xliii. 563, 564; Jukes-Browne, Stiatlgraphical Geology (1902), p. 442. 6
 * See F. J. Bennett, 'Geology of Bury St. Edmunds and Newmarket,' Geol. Survey (1886), p. 2.
 * Whitaker and others, ' Geology of Parts of Cambridgeshire and Suffolk,' Geol. Survey (1891), p. 4.