the Displacement of Shore-lines. 517 



Oligocene horizons in this series : — the Middle Headon, Bem- 

 bridge Oyster-bed, and Hamstead Corbula-beds. The Middle 

 Headon is regarded by palaeontologists as synchronous with 

 the marine gypsum in the Paris-basin. I have fitted the 

 Paris beds, so that the marine gypsum coincides with the arc 

 3', and the Fontainebleau Sands with the arc 7'. If we now 

 arrange the equivalent beds in the Isle of Wight in the same 

 arcs, we see that the Isle of Wight profile tits perfectly into 

 the curve of eccentricity, as follows : — 



Lower Headon to the arc 2' and perhaps the last part of 1', 

 with 7 alternations and 7 pi-eeessions. 



Middle and Upper Headon, with 5 alternations, to the arc 

 W , with 5 precessions. 



Osborne, with 10 alternations, to the arcs 4' and 5', with 10 

 precessions. 



Bembridge, Avith 6 oscillations, to the arc 6', with 5 or 6 pre- 

 cessions. 



Hamstead, with 3 alternations, to the first part of arc 1', 

 with 3 precessions. 



It thus appears that the 3 marine horizons coincide with the 

 3 highest eccentricities, the summits of the arcs 3', 6', and 7', 

 while the lower arcs and parts of arcs correspond to brackish 

 and freshwater beds. The most unmixed freshwater forma- 

 tion, the Osborne, coincides with the two lowest arcs, 4' 

 and 5'. 



For the sake of comparison, we will again carefully go 

 through the profile of the Paris basin, and compare this with 

 Stockwell's curve, commencing from the bottom. The beds 

 are numbered in the same way as in the original description 

 of Dollfus and Vasseur {Bull. Soc. Geol. Ft. ser. 3, torn. vi. 

 1878, pp. 243, et seqq.). 



Sables de Beauchamp et Mortefontaine &c., beds 89-111. 

 — Arc 14 and first half of 15. In this series we have, first 

 5 marine sandstones alternating with sand ; then a limestone 

 and a calcareous marl, with intercalated sand and marl. Thus 

 in all 6 or 7 alternations. 



Calcaire de St. Onen, beds 112-142. — A freshwater forma- 

 tion which is divided by a marine deposit (128) into two 

 subdivisions. In the lower part (from the summit of arc 15 

 to the summit of arc 16) there are 4 horizons of hard lime- 

 stone and siliceous limestone with intercalated marls. Then 

 comes the marine bed (at the summit of 16). It must be 

 remarked that the corresponding arc in Leverrier's curve 

 reaches higher up. In the upper division of freshwater 

 limestones we have 6 alternations of hard limestone and 



