150 Tertiary. 



He described, from Maryland, in strata now regarded as of Pliocene 

 age, Murex acuticosta, Volufa soUtaria. Cassis ccelata^Trochus humilis^ 

 T. reclusus, Pyrula sulcosa, Turritella laqueata.^ T. variabilis., Can- 

 cellaria lunata; and from strata now referred to the Miocene, Natica 

 fragilis, Pleurotom'a communis, P. dissimilis, P. parva, P. rotifera, 

 31arginella denticulata, ITassa quadrata, Terebra simplex, Actaeon 

 melanoides, A. ovoides, Mactra ponderosa, Venus alveata, AmpJii- 

 desma carinatum. Area maxillata, and Cardium laqueatum; and from 

 strata now referred to the Eocene, 3Tonodonta glandula, Turritella 

 mortoni, Cucullcea- gigantea, now Latiarca gigantea, Crassatella alae- 

 formis, and Venericardia blandingi. 



Id 1832, Prof. Edward Hitchcock* described the alluvium as that 

 fine, loamy deposit, which is yearly forming from the sediment of run- 

 ning w^aters, chiefly hy the inundations of rivers. It is made up oi 

 the finest and richest portions of every soil over which the waters have 

 passed. No extensive alluvial tracts occur in Massachusetts; although 

 limited patches of this stratum exist, not infrequently, along the banks 

 of every stream. The diluvium., he said, occupied more of the surface 

 of the State than any other stratum. It is not generally distinguished 

 from alluvium; but it is usually much coarser, being made up, com- 

 monl}'', of large pebbles, or rounded stones, mixed with sand and frag- 

 ments of every size, which are often piled up in rounded hills to a con" 

 siderable height, and under such circumstances as preclude the proba- 

 bility that it could have resulted from existing streams. The Tertiary 

 formation is represented as most perfectly developed on Martha's 

 Vineyard, though found on the Connecticut river avid in the vicinity 

 of Boston, and in limited patches in other parts of the State. He said 

 the difl^erence between this formation and the diluvium is, that in the 

 diluvium, the sand, pebbles and clay are confusedly mixed together; 

 but in the Tertiary, these materials are arranged in regular, and gen- 

 erall}', in horizontal layers, one above another. Hence, when the sandy 

 stratum happens to lie uppermost, the soil will be too sand}^; but ii 

 this be worn awa}', so that the clay lies at the surface, the soil will be 

 too argillaceous; or if the gravel stratum be exposed, the soil can not 

 be distinguished from diluvium. 



In 1833, f he treated of the coast alluvium, which is produced by tides 

 and currents in the ocean, that frequently transport large quantities 

 of soil from one place to another, and cause it- to accumulate in those 



- Rep. on the Geo. of Mass., 1832. 

 f Rep. on the Geo. of Mass., 5833. 



