46G DIFFERENT LAYERS OF THE BED; 



sive or tough does not bend to pressure, but breaks cuts 

 smooth, except when the edge of the knife meets parts of shells, 

 or grains of silicious sand, which, as well as granules of green- 

 sand, are irregularly intermixed throughout. The shells very 

 rotten, and flattened by pressure. Sometimes in masses, or thin 

 bands or regular layers, becoming less and less in quantity as 

 descending, and but few seen at and below 10 feet of this stra- 

 tum. Numerous particles of mica throughout. Changing gra- 

 dually to next. At 12 to 13 feet of its depth, many hard lumps 

 of. sulphuret of iron. The upper three or four feet of this 

 penetrated by numerous hollow cylinders, of an inch or more in 

 diameter, and in every direction obviously having been bored 

 by shell-fish. These hollows are filled by the green earth of the 

 stratum above, which thus makes nearly half the mass. (This 

 clay and the layer above (D) were the kinds used for manure 

 from the first opened pit.) 



3 feet (22 to 25 below tide) of brownish and more friable clay, in- 

 termixing at first with the above. Green-sand much more 

 abundant than in the preceding, and partly in very large granules. 



3 1 feet (25 to 28 below tide) of very smooth and firm clay, of 

 delicate lilac colour at first, but becoming paler as descending, 

 until nearly white. Splits easily into flakes like thick slate ; and 

 still thinner laminao show that the earth was a deposit in tranquil 

 waters. Thin flakes (not thicker than writing paper), and some- 

 times a mere powder of pure sulphuret of iron visible between 

 many of the layers of clay, and causing them to separate easily. 

 The upper foot of this penetrated everywhere by small hollow 

 tubes (from an eighth to the third of an inch in diameter), which 

 are filled by the brown and green variegated earth of the stratum 

 above causing a lump when cut smooth to appear like a con- 

 glomerate of differently coloured marbles. Except in these bor- 

 ings, no green-sand deposit, and no shelly matter. The sulphurefc 

 of iron, which is through this stratum visible in powder, or thin 

 layers, and above in small masses or lumps, is diffused through 

 all the strata containing green-sand, except the highest (6 Y ). 

 Through this and the upper gray clay (E} some small black 

 pebbles seen, which appear as if formed by melting. The same 

 found in the eocene marl. A sudden change to the next 



2 feet (28 J to 31 below high tide) of remarkably smooth and 

 unctuous, but firm clay of reddish brown colour (or dull brick 

 red), and homogeneous texture as well as colour. Cuts as smooth 

 as the best hard soap. Deposited in thin laminae, and breaks or 

 splits easily in straight lines both in the direction of the laminae 

 and lengthwise at right-angles to their direction the grain and 

 fracture appearing like that of rotten wood. Across these two 

 directions, the fracture very uneven. Near the bottom of the 



