66 JVotes on JYatural History. [Jan., 



NOTES ON NATURAL HISTORY, ETC., 



EY JAMES EIGHTS. 



De la Beche remarks that " it not unfrequently happens that in 

 clays, containing disseminated carbonate of lime, there are nodules 

 more calcareous than the other parts, and which we readily per- 

 ceive are not bodies rounded previous to deposition, although at a 

 distance they have that appearance;" and in a note Prof. Hitch- 

 cock adds, " these concretions generally go by the name of clay- 

 stones, and are regarded as the result of running water; though 

 not unfrequently they have been considered as the work of man. 

 Indeed I have never seen any thing in the mineral kingdom that 

 had so artificial an aspect." — Geological Researches. 



These argillo-calcareous concretions are exceedingly common 

 in the lacustine marly-clay in the vicinity of Albany. They are 

 strictly confined to the upper part, or that part which is most com- 

 monly made use of for the manufacturing of brick. The manner 

 in which they have been found, is distinctly perceptible every 

 where among the various and extensive diggings, which have 

 thrown them open to the light of day. The strata among which they 

 are usually found is in a horizontal position, not unfrequently separa- 

 ted by thin seams of a remarkably fine sand; the delicate fibres of 

 the roots of the different trees of the forest, that at one time com- 

 pletely covered the surface of the soil, have, in innumerable pla- 

 ces, penetrated to a very considerable distance beneath; it was 

 along these roots that the moisture from the surface, highly charged 

 with carbonic acid, has readily found its way, collectmg the lime 

 and other necessary materials as it descended, until its arrival at 

 one of these seams; here a deposition connnenced, and the parti- 

 cles gradually arranged themselves in a concretionaiy form, 

 around a nucleus of ligneous fibre. Whenever these concretions 

 have been examined in a perfect state, the nucleus, or remnants of 

 it, has invariably been found, exhibiting no other change in its 

 appearance than that of a brownish stain given to it by the oxide 

 of iron. Sometimes two or more of them are united together; at 

 others, where the deposition seems to have been far more copious, 

 the liquid mass appears to have spread out to some considerable 

 extent, giving origin to those stony plates of the same nature, 

 which are always to be found associated with them. It is, also, 

 not an unusual circumstance for many of them to be marked with 

 circular depressions, where, after a short exposure to the atmos- 

 pheric influences, they readily disunite, the central portion falls 

 out, carrying with it the woody nucleus, which it contains, and 

 leaves the concretions in that very regular ringlike ibrm that they 

 so commonly assume. 



