hetioeen Christchurch Head, Hampshire, and Studland Bay, Dorsetshire. 283 



was worked in the interior near Bourn Mouth. Alum sometimes effloresces 

 from some of the clays associated with the white sand where they contain 

 pyrites. 



This series of sands, clays, and argillaceous marls, is nowhere exposed to 

 view, so that the entire thickness of the whole cannot be accurately estimated ; 

 but it is not less than 150 feet. The cliffs vary occasionally in height, but 

 except where interrupted by chines and valleys, they are rarely less than 60, 

 and appear never to exceed 130 feet. The inclination of the beds is slight, 

 but in the sections in some of the Chines a slight dip to the north is seen. 

 Gentle curves and undulations in the strata are not uncommon, as about a 

 mile east of Boscomb, and between Boscomb Chine and Bourn Mouth. The 

 strata of sand are not always conformable ; and this unconformability has 

 arisen from irregularities attending their original deposition, and not from 

 any subsequent disturbances or slips. The diluvium covering this line of 

 cliffs varies from 10 to above 40 feet in thickness, and is chiefly composed of 

 flint-gravel. Sand, however, is in some parts intermixed, and often interstrati- 

 fied with considerable regularity. 



After passing Bateman's Chine and the cliff on which the Flag-house 

 stands, the section is interrupted by the mouth of Pool Harbour, and the bar 

 of sand on each side of it, for a space of about two miles and a half. The 

 section is resumed near Studland ; but the strata are not continuously exposed, 

 and the junction of the plastic clay-formation and the chalk is very imperfectly 

 exhibited. First, at a spot a few hundred yards to the north of Studland, in a 

 sloping inland cliff protected from the sea by alow sand-bank, yellow and pur- 

 ple sands are seen, and in a few spots, pipe-clay. Nearly opposite the viflage 

 of Studland, where the section first becomes distinct, the following strata occur, 

 beginning with the uppermost. 



1. Vegetable soil 2 feet 



2. Yellow and purplish sand (PI. XXX. No. l.j.) 10 



3. White sand, alternating with thinly laminated white clay, containing a quan- 



tity of vegetable remains (PI. XXX. No. 1. k.) 20 



4. Sand, occasionally passing into sandstone. 



This last bed strikingly resembles some of the ferruginous sand of the 

 Shanklinbeds containing similar ferruginous concretions in balls, or, as in the 

 Isle of Wight and Sussex, in long tubes 6 feet (See PI. XXX. No. 1.1.). Pr6- 

 ceedingtowards the chalk, we find the cliff occupied by sands mottled with white, 

 yellow, and purple (PI. XXX. No. 1. m.). These cliffs are sometimes very 

 beautifully marked with concentric stains, exactly imitating the transverse and 

 oblique sections of trunks of trees ; and the sand often passes into sandstone. 



