244 Oldhaven Beds. 



0. elegans, &c. ; Pectunculus, Psammobia, &c. ; Crus- 

 tacea (Hoploparia, gammaroides) and Foraminifera 

 also occur. 



A few land-plants have been found, as might be ex- 

 pected in estuarine strata, viz. Dryandroides Prest- 

 wichi, figs, laurels (L. Hookeri), Grevillia Heeri, and 

 Robinia Readingensis ; also great numbers of fresh- 

 water shells in true fresh-water strata, such as Paludina 

 Lenta, &c. ; Planorbis Icevigatus, &c. ; and several of 

 the genera Cyrena (G. cordata, &c.) and Unio, together 

 with the small bivalve Entomostraca, Cypris and 

 Cythere. 



Taken as a whole, the estuarine, and especially the 

 fresh-water character of so many of the strata of this 

 series, make the strongest impression on anyone engaged 

 in mapping them. 



The Oldhaven beds, formerly included by Mr. 

 Prestwich in the basement bed of the London Clay, lie 

 between the above-named strata and the London Clay, 

 and consist of fine sand containing water-worn pebbles 

 of flint. They are of inconsiderable thickness, but very 

 constant in their occurrence. With the rarest excep- 

 tions the fossils are marine ; and they are numerous, 

 consisting to a great extent of the same molluscous 

 genera as those found in the Eocene strata below, with 

 additions, and a proportion of the species are also found 

 in the overlying London Clay. Their chief importance 

 in this sketch is, that the sand with water-worn pebbles 

 seems to indicate some oscillation of level, accompanied 

 by stronger currents, in an estuary which carried flint- 

 pebbles onward, toward the mouth of this old river. 



The London Clay (fig. 47, p. 241), is a marine de- 

 posit, in the sense that the strata now forming in the 

 broad estuary of the Amazons is marine. It usually con- 



