Page:VCH Suffolk 1.djvu/60

 A HISTORY OF SUFFOLK Near Sudbury the Drifts are intensely contorted, and yet in places they rest on seemingly undisturbed Tertiary strata, a fact explained by Mr. J. E. Marr on the supposition that the naturally soft strata had been frozen into a hard and unyielding condition. At the same time in places the Boulder Clay contained fragments torn off the underlying for- mations.' Contortions are often prominent where Boulder Clay rests on laminated clays and sands, as to the west of Bury St. Edmunds and at Halesworth Kiln. Disturbances are also met with in the Crag Series at Ipswich, and in the Chalk at Botesdale, where overlain by Boulder Clay. Some curious and possibly slipped masses of Boulder Clay have been observed in the cliffs at League Hole near Corton.' In connexion with these it may be interesting to mention, on the authority of the late J. H. Blake, that when Sir Morton Peto made the esplanade at Lowestoft he protected the cliff at Kirkley by tipping a lot of Boulder Clay down the face of the cliff. While the Boulder Clay weathers into a brown stony loam not unlike the loam of the Contorted Drift, it forms the heavier lands (the ' strong loam ') of central and south-western Suffolk and of small areas elsewhere. Wheat and beans and also barley flourish on the soil. The district in places is well wooded, and the hedgerows are luxuriant ; in- deed, the so-called ' woodlands ' of High Suffolk form a part of this Boulder Clay tract. It is not to be regarded as a water-bearing formation, and yet it includes beds of sand and gravel which here and there yield supplies of water, sometimes of an artesian character. Such supplies are apt to fail in seasons of drought. Ordinary bricks and pottery are in a few places manufactured from the Boulder Clay, as near Ipswich and Burgh Castle, while elsewhere sun-dried bricks are made from the clay mixed with chopped straw. VALLEY DEPOSITS Deposits of gravel and loam of later age than the Boulder Clay occur under two distinct conditions. The older are high level deposits connected with a system for the most part distinct from that of the present drainage, but sometimes initiating it. Some of the coarse gravels which overlie the Boulder Clay are of this character. There are also ancient lacustrine deposits. Succeeding the main glaciation represented by the Boulder Clay, and when, as Mr. C. Reid points out, the land stood somewhat higher than at present, the streams excavated channels, as at Hoxne, ' slightly below that of the present main channel of the river Waveney.' Gradual subsidence turned the Hoxne channel into a shallow freshwater lake, • Geol. Mag. (1887), p. 262. ' Rev. E. Hill, ^art. Journ. Geol. Soc. Hi. 302 24