CONCEETIONS. 711 



be small place for any influence of torsion. Yet from the removal of the 

 clay to produce the bluft', and from the quite sudden drying of the surface 

 of the bluff, there might be a slight creeping of the clays still below the 

 level of the streams, or the wet floor of the clay pit might produce torsion, 

 which would be influential in producing the forms observed. 



Concretions. — In the Journal Book of the Royal Society for 1734 is a 

 manuscript catalogue of objects of natural history found in New England, 

 by John Winthrop, magistrate of tlie Connecticut colony and great-grandson 

 of the first governor of Massachusetts. It mentions "clay generated in the 

 form of horse shoes from the bottom of Connecticut River." ' It would 

 be difficult to find a boy brought up near the Connecticut who had not in 

 the early summer gathered claystones on the bank of the river which had 

 been washed out of the clay in the spring floods, and wondered at their 

 abundance, their smooth and apparently artificial surface, and their regular 

 form — spherical, spheroidal, ellipsoidal, or flattened into disks, sometimes 

 variously elongated, lobed, or grotesquely imitating animals and works of 

 art. And he would be hardly satisfied with the common explanation that 

 they were formed from hardened pieces of clay by the wearing of the 

 water. This was Dr. Hitchcock's first opinion, and in 1823^ he gave a full 

 mineralogical description of them. They thus very early attracted the 

 attention of the geologist, and in 1835 President Hitchcock describes them 

 with care, and asks the questions: "But are concretions the result of crys- 

 tallographic laws! If so, why are not crystals pi'oduced!" The tubular 

 ferruginous form he describes as a fossil of uncertain character.^ In the 

 report of 1841 he devotes 16 j^ages and 5 plates to a discussion of concre- 

 tions, and presents a classification of them according to form; and though 

 he no longer looks upon any of them as fossils, he considers them exceed- 

 ingly difficult of explanation and thinks one must assume them to be the 

 result of the action of galvanic electricity, and associates with them, as a 

 result of the same general causes, the prismatic blocks of clay produced 

 by shrinkage joints which I have described on page 709. 



President Hitchcock returns to the subject in 1861, in the report on 

 the Geology of Vermont, and devotes 8 pages and 3 plates to clay- 



' Am. Jour. Sci., 1st series, Vol. XLVII, p. 282. 



'^Geology of the Connecticut River: Am. Jour. Sci., 1st scries, Vol. VI, 1823, p. 229. 



^Geol. Mass.. p. 182. 



