THE DIFFERENT LAYERS. 463 



streaked with yellow ochre, and full throughout of very minute 

 crystals of sulphate of lime, supposed by the eye to be about 10 

 to 15 per cent, of the whole mass. No shells or casts seen in 

 the part exposed by digging for examination. 



7 feet of brownish mottled clay, feeling smooth and soapy, con- 

 taining numerous small crystals of sulphate of lime. 



9 feet very pure white clay or fuller's-earth, in horizontal layers, 

 separated by veins of the yellow clay (or iron ochre) before- 

 mentioned, other veins of the same sometimes also inclined and 

 crossing the horizontal veins the outsides of the lumps of clay 

 coloured by oxide of iron. The clay all broken into irregular 

 lumps, as if the fissures had been formed by the contraction in 

 drying of clay soft and distended with wetness. No shells, nor 

 appearance of them, but many pure and transparent and beauti- 

 ful crystals of sulphate of lime here and there, some weighing 

 several ounces. This stratum changing gradually into the next of 



4 feet of dark bluish clay, the colouring matter being green-sand, 

 mottled with irregular streaks of bright yellow, becoming brown 

 below where oozing water begins to show and is reddish with 

 sulphate of iron, or other ferruginous matter in solution. This 

 stratum full of large and solid crystals of sulphate of lime, 

 amounting apparently to from 20 to 25 per cent, of the whole 

 mass the crystals coloured dark gray, because of some impu- 

 rities in small grains (green-sand ?) being enclosed and diffused 

 through them. No shells. This changing into the next, of 



11 feet of same dark or nearly black clay, nearly uniform colour, 

 and still compact texture, and feeling smooth and soapy with 

 very few crystals, and much less sulphate of lime than the pre- 

 ceding, but many small and scattered eocene white shells, quite 

 rotten, and being moist, as soft as dough. The shells, mostly 

 several kinds of very large turritellae. Fewer shells as descend- 

 ing. At top of the stratum some large and very perfect speci- 

 mens of the ostrea compressirostra (/) To level of the river at 

 common high tide. 

 Below high tide. 



14 feet very similar to the last, the shells very few for the greater 

 part, but increasing near the next. No crystals or other sulphate 

 of lime visible. The green-sand granules coarser sometimes 

 in small lumps quite pure, or unmixed with anything else. 

 These granules breaking easily, though as if hard or brittle, and 

 not like a soft soapy clay as usual though as green as before. 

 Many small cylindrical tubes seen (made by the burrowing of 

 pholades, or other shell-fish of the like habits), which seem to 

 be formed on, or coated with pure green-sand in mass, and green 

 in colour, and the hollows filled with looser black granules. 



11 feet of shells lying generally close together, and serving -to 



