496 A. Blytt on the probable Cause of 



Sac. Gdol. Fr. 1878, pp. 243 et segq.) shows the following 

 oscillations and alternations of strata, and may, as regards the 

 continuous portion, fit into Stockwell's curve, as appears from 

 the arc-numbers cited for each oscillation : — 



Sables de Cuise, marine. 



Calcaire grossier inferieur et moyen, marine, with 7 alter- 

 nations. 



Calcaire grossier ; Caillasses a Cerithium, 2 marine alter- 

 nations, and between them a deposit with freshwater 

 shells. 



Calcaire grossier ; Caillasses a Lucina, marine, with 5 

 alternations. 



Calcaire grossier : Caillasses a Cardium, marine, with 11 

 alternations. Gap in the series. 



Sables de Beauchamp, freshwater and marine, about 4 

 alternations. Arcs 14-15. 



Calcaire de St. Ouen, freshwater, 4, above which a marine 

 deposit (summit of arc 16), then 6 freshwater alter- 

 nations. Arcs 15-2'. 



Gypsum, marine, about 11 alternations. Arcs 2'-4'. 



Gypse palustre, freshwater, about 6 alternations. Arc 5'. 



Marne verte, brackish, 2 alternations. Arc 6'. 



Calcaire de Brie, freshwater, 1 alt. Between arcs 6' and T. 



Marne et Mollasse, sables de Fontenaye, marine, 3 alter- 

 nations. Arc 7'. 



Meulieres de Montmorency, Calcaire de Beauce (p. p.), 

 freshwater. Between arcs 7' and 8'. 



There is only one discrepancy : — Arc 16, the summit of 

 which should correspond to the marine deposit in the middle 

 of the Calcaire de St, Ouen, does not go so high that we 

 should expect an inundation of the sea. But the oscillation 

 is at any rate also indicated in Stockwell's curve, and the 

 marine formation consists of a single bed, and is so faintly 

 marked that it has only recently been recognized. 



Another profile from another place in the Paris-basin (la 

 Frette, JBuU. Sac. Gdol. Fr. 1876, pp. 471 et seqq.) has the 

 same number of alternations as the above and extends from 

 13 to 2'. The marine bed at 16 is wanting in this profile, 

 otherwise the same oscillations are indicated. 



The profile at Mery-sur-Oise has in all 71 alternations of 

 strata, of which 25 are in the Calcaire grossier. A great 

 part of the calculated curve is therefore filled up by the oc- 

 currence of 37 alternations without a gap in the series of 

 deposits. With arc 1' the marine formations of the basin 



