andSatid called " Sand-pipeSy" in the Chalk near Norwich. 26 1 



dently elbows of tortuous sand-pipes, the other parts of which 

 had been removed during the excavation of the pit. The 



Fig. 2. 



Tortuom Sand-pipes in the Chalk at Heigham, near Norwich, from a drawing 

 by J. B. Wigham, Esq. 



layer of chalk flints, c, is far from being horizontal, as will 

 be seen by the sketch, and seem to imply that the chalk has 

 been disturbed. 



" At Hellesden, about 3 miles N.W. of Norwich, where 

 similar appearances are exhibited in a chalk pit 20 feet deep, 

 the upper extremity of one pipe, 5 feet in diameter, is covered 

 by undisturbed layers of chalky rubble resembling chalk, al- 

 ternating with fine clay for a thickness of four feet. One of 

 the pipes in the same pit measures no less than 2S feet across, 

 its depth being unknown. 



"At Thorpe is a sand-pipe (see fig. 3.) which is 20 feet in 

 diameter where it enters the chalk. It is filled with gravel, 

 sand, clay, stones, and chalk-flints. It penetrates through 35 

 feet of chalk, tapering downwards very gradually. It is remark- 

 able for the regularity with which it continues its course through 

 10 feet of sandy strata, A A, which overlie the chalk, some 

 beds of which, as at 6, are rich in the shells of the Norwich 

 crag. A layer of light-coloured sandy clay, c, fig. 3. (indicated 

 by dots) lines the sides of the pipe for many yards, both where it 

 passes through the chalk and through the overlying arenaceous 

 beds A; this same clay also continuing its course horizontally 

 beyond the opening or upper end of the pipe. The dark bed, d, 

 fig. 3. which is in contact with this clay, is an indurated layer 

 of sand coloured by oxide of iron, which contains casts of 

 marine shells, not only where horizontal, but in that part also 



