CALCAREOUS MANURES— APPENDIX. 217 



of lime, supposed 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, containing nu- 

 merous small crystals of sulphate of lime. 



9 feet very pure white clay or fuUer'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 colored 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 beautiful 

 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 coloring 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 25 to 35 per 

 cent, of the whole mass— the crystals colored dark gray, because of some 

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

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



1 1 feet of same dark or nearly black clay, nearly uniform color, and still 

 compact texture, and feeling smooth and soapy— with very few crystals, 

 and much less sulphate of liiBC than the preceding, 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 turritellas. Fewer 

 shells as descending. At top of the stratum some large and very perfect 

 specimens of the ostrea compressirostra.Q) To level of the river at com- 

 mon 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 any thing 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, which 

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

 in color, and the hollows filled with black granules. 



1 1 feet of shells lying generally close together, and serving to make the 

 whole stratum a calcareous marl, of perhaps 30 per cent, or more of carbo- 

 nate of lime— the earth filling the shells and between them being the 

 same black earth, as rich as before in green-sand. At top, some very 

 large and perfect shells of ostrea compressirostra, and another much 

 thicker ostrea, not known.* The shells mostly very large turritellce of 

 different species— near bottom fewer of these and mostly crassatellce. 

 The shells nearly as numerous as before, at this depth, at which the dig- 

 ging was abandoned, at 25 feet below tide. 



The whole section, from the top of the highest undoubted eocene 

 stratum to where the digging ceased, (without any indication of being 

 near the end,) is 61 feet — and if the clay and gypsum stratum below the 



• One of these last (both valves) weighed 5 lbs. Mr. M. Tuomey, to whose much 

 better information on this subject I ought to defer, supposes this very large and heavy 

 shell to be an 0. compressirostra of unusual age and growth. If so, however, it is cer- 

 tainly very different in appearance from that shell, as usually seen higher up in this 

 bed, even when wider than the very thick and heavy ostrea. 



