Oolitic Formation of Saratoga County, MY. 17 



The calcareous concretions, which characterize and 

 identify this formation, are, for the most part, arranged in 

 successive layers throughout the strata in which they ap- 

 pear; they are globular, of the size of mustard seed, pos- 

 sess a shining black color, and are evidently composed of 

 concentric layers. They are united in the mass by a cal- 

 careous cement, more or less granular, combined with fine 

 siliceous sand. 



More than one half of the whole mass of some of the 

 strata, which constitute the series of this formation, con- 

 sists of these globular concretions ; in others they are more 

 sparingly diffused, and some of the strata appear to be 

 composed altogether of a calcareo-siliceous sand, without 

 the intervention of a single globule, these are mostly of a 

 darkish grey cast, but they are in some place?, rendered 

 brown by the intervention of ferruginous particles ; they 

 strongly resemble some varieties of graywacke, and, with- 

 out a close inspection, might easily be mistaken for it. 



In and near the road, which leads from Greenfield to 

 Ballston-spa, by the w-ay of Rowland's mills, on the farm 

 of Deacon Wood, there is a bank composed of a series of 

 horizontal strata where the peculiar characterisiic features 

 of this formation are well defined and may be readily ex- 

 amined. 



One of the strata, which compose the series at this place, 

 presents a very singular appearance, and one which, if it 

 occurs elsewhere, has never been noticed, so far as I am 

 able to learn, by any writer. The surface of this stratum 

 is fairly exposed for a number of rods both to the norih 

 and south of the bank beneath which it evidently passes, 

 it is about two feet in thickness and has imbedded, through- 

 out its substance, great quantities of calcareous concretions 

 of a most singular structure; they are mostly hemispheric- 

 al, but many of them are globular and vary in size from 

 half an inch to that of two feet in diameter; they are ob- 

 viously composed of a series of successive layers, nearly 

 parallel and perfectly concentric; these layers have a corn- 

 infer this from the fact, that your locality holds the same relative position, 

 and from the peculiar character of that rock. In addition to this, I have 

 seen in connection with it, the same calcareous grit, (as the English au- 

 thors call it,) which you sinewed me as being connected with the Saratofa 

 Oolite." 



Vol. IX.— No. 1. 3 



