49 



NOTES ON SOME CLAY CONCRETIONS FROM 

 THE CONNECTICUT VALLEY, U.S.A., 



By W. Swanston, F.G.S. 



{Abstract.) 



In introducing this remarkable series of concretionary 

 nodules I should state that, as I have not personally collected 

 them, I am unacquainted with such details of their occurrence 

 as I should have been glad to bring before the meeting. They 

 were collected near Hartford, U.S.A., in beds of the Triassic 

 series. Nodules and concretions of similar character occur in 

 most sandstone and clay deposits irrespective of geological age. 

 We may therefore safely infer that, under similar conditions, 

 their mode of formation will be somewhat alike. The following 

 appears under the heading " Concretions" in an authority 

 consulted. " Concretions are nodules, balls, or irregular 

 masses which occur scattered through the body of the rock, and 

 consist of mineral matter which was formerly diffused through 

 the material of the rock. Some are crystalline, as gypsum in 

 clay ; others may have mternal radiating structures, as iron 

 pyrites in shale, etc. Fantastically shaped concretions are not 

 uncommon in fine clays, and are known as 'fairy stones' by the 

 country folk in some districts. They are produced by mole- 

 cular aggregations subsequent to the deposition of the strata, 

 whereby the substance of the rock is forced into spherules or 

 balls." Similar nodules, but of less delicate form and texture, 

 are occasionally found in stream courses cutting through the 

 new red sandstones of County Antrim, the softer body of the 

 rock having been removed by the action of the water, the 

 concretions are found adhering to the sides of the miniature 

 canyons. The extremely delicate character of the examples 

 exhibited is doubtless due to the finer texture of the rocks in 

 which they were found. Their stratified appearance — which 



