CALCAREOUS MANUKES^APPENDIX. 



219 



liaving nearly the texture of clay marl. Very compact and firm in tex- 

 ture — unctuous to the touch, but not adhesive 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 gra- 

 nules 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 descend- 

 ing, and but few seen at and below 10 feet of this stratum. Numerous 

 particles of mica throughout. Changing gradually 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 (/>) were the kinds used for manure from the first opened pit.) 



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

 at first with the above. Green-sand much more abundant than in the 

 preceding, and partly in very large granules. 



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

 color at first, but becoming paler as descending, until nearly white. 

 Splits easily into flakes like thick slate ; and still thinner laminae show 

 that the earth was a deposite in tranquil waters. Thin flakes (not 

 thicker than writing paper,) and sometimes a mere powder of pure sul- 

 phuret of iron visible between many of the layers of clay, and causing 

 them to separate easily. The upper foot of this every where penetrated 

 by small hollow tubes, (from an eighth to the third of an inch in diame- 

 ter,) 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 diiferently colored marbles. Except in these borings, no 

 green-sand deposite, and no shelly matter. The sulphuret 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 (C) 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 (28i to 31 below high tide) of remarkably smooth and unctuous, 

 but firm clay of reddish brown color, (or dull brick red,) and homoge- 

 neous texture as well as color. Cuts as smooth as the best hard soap. 

 Deposited in thin lamini«, 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 richest green stratum (Z>) there is a barely perceptible oozing of 

 water. All below dry, and the two last strata remarkably dry. They 

 could not be more so if within three feet of the surface of a high knoll. 



1 foot (31 to 32 below tide) of same as the last in texture, but of pale blue 

 color. 



1 foot (32 to 33 below tide) mixture of the last, in small lumps imbedded in 

 the next, as if broken up by a violent current, and deposited in rapid water. 

 17 feet (33 to 49 below tide, the lowest digging,) black earth— richest in 

 green sand (supposed to be 60 per cent) mixed with a (e\w fragments 

 (less than 2 per cent, on an average) of shells— mostly small, and all very 

 rotten. Kinds, mostly of turriteUa (some of which are large,) mytylus, 

 corhula and crassatella. Many small and a few large shells of osirea 

 compressirostra near top of this stratum and again near the lowest part, 

 where the work was stopped by the water rising from below. 



