GEOLOGY 



Where exposed at the surface the London Clay would under ordi- 

 nary circumstances yield a stiff clayey soil, but in Suffolk it is mainly 

 exposed along the borders of valleys and the soil is lightened and en- 

 riched by down washes from higher sandy and shelly strata. The soil 

 has therefore been described as a ' rich loam,' and as such it is met 

 with here and there from Hadleigh eastwards to the borders of the Stour, 

 Orwell and Deben. 



It is impossible now to say how far the Eocene strata formerly ex- 

 tended over Suffolk. In some areas deep ' pipes ' in the Chalk have 

 preserved portions of the strata at a distance from the main mass, but 

 apart from the doubtful evidence furnished by well sections no such 

 relics have at present been proved to occur in Suffolk. 



It may be that there was overlap of the successive members of the 

 Eocene series, and that Bagshot Beds formerly extended into the county, 

 yielding materials for some of the Pliocene and Glacial sands and pebble 

 beds. Indeed, S. V. Wood, jun., suggested that the middle Glacial 

 sands might largely have been made up of Bagshot Beds.' The occur- 

 rence moreover of Oligocene fossils in the basement beds of the Crag 

 in Norfolk is also a significant fact. 



The Chalk surface has been furrowed in places by ' pipes ' and traces 

 of clay-with-flints were noticed by Mr. F. J. Bennett in such pipes 

 beneath Boulder Clay near Saxham," while irregular channels have 

 occasionally been formed in Pleistocene times and filled with Glacial 

 Drift. 



Some disturbances have been proved in the Chalk south of Ipswich 

 and at Woodbridge,^ while a few small faults have been noticed in the 

 London Clay at Felixstow and Bawdsey. 



PLIOCENE 



The Crag Series consists of sands, pebbly gravels and laminated 

 clays, but the characteristic and prominent beds are shelly sands which 

 have for a long period been dug as manure for fertilizing the land and 

 as material for garden walks.* 



CORALLINE CRAG 



The lowest division, known as the Coralline Crag, owes its name 

 to the fact that much of it is composed of bryozoa. In some places it 

 appears in the form of loose shelly sands ; elsewhere it is composed of 

 comminuted shells and bryozoa, locally hardened into stone, the joints 



• ' Remarks in Explanation of Map of the Upper Tertiaries of the Counties of Norfolk, Sufiblk, 

 etc' (1866), p. 13. 



' * Geology of Bury St. Edmunds,' p. 12. 



' Whitaker, ' Geology of Ipswich,' p. loo ; and ^uart. Joum. Gnl. See. lix. 



* For full particulars of the Pliocene strata, see S. V. Wood, 'The Crag Mollusca,' PaUmtograph. 

 Soc. ; Prestwich, Quart. Journ. Geol. Soc. xxvii. 115, 325, 452 ; F. W. Harmer, ibid. liv. 308, lyi. 

 705 ; Whiuker, 'Geology of the country around Ipswich,' p. 32 ; C. Reid, 'The Pliocene Deposits 

 of Britain' (1890), Geol. Survey ; and E. T. Newton, 'The Vertebrata of the Pliocene Deposits of 

 Britain ' (1891), Geol. Survey. 



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