374 ON THE MOVEMENTS OF THE EARTH's CRITST. 



lowerarcsand parts of arcs correspond to brackish and frcsii-water beds. 

 The most unmixed fresli-water formation, the (Jsborne, 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. 

 Fr., 1878, ser. 3, tom. VI, pp. 243, et seq.). 



Sables de Beauchamp et Mortefontaine, etc., beds 89 to 111. Arc 14 

 and first half of 15. In this series we have, first five marine sandstones 

 alternating with sand ; then a limestone and a calcareous marl, with in- 

 tercahited sand and marl. Thus in all six or seven alterations. 



Calcaire de St. Ouen, beds 112 to 142. A fresh- water formation 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 10) there are 

 four horizons of hard limestone and siliceous limestone with intercal- 

 ated marls. Then coqies 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 fresh-water limestones we 

 have six alterations of hard limestone and siliceous limestone with marl 

 and clay. This division therefore finishes a little to the left of the sum- 

 mit of arc 2'. 



Sablas de 3£onceaux, beds 143 to 145. Marine sand with three Septaria 

 layers. The rest of arc 2'. 



Marnes a Pholadomya, beds 146 to 154. Marine, with two alterations 

 of siliceous limestone and marl. The first part of arc 3'. 



Gypsum No. 3, beds 155 to 158. Marine marl and gypsum, one al- 

 ternation, and Marnea Luciana, bed 159. The rest of arc 3'. 



(The beds 146 to 159 thus have together three alternations and corre- 

 spond to the arc 3'.) 



Gypsum No. 2, beds 160 to 196, arc 4'. Marine, at any rate for a great 

 part. But it must be remarked that no fossils have been cited from the 

 last part of this series. Gypsum alternating with marls about five 

 times. The most important gypsiferous horizons are the beds 161, 171 

 to 176, 178 to 188, 191 and 194. 



Gypsum No. 1, bed 197, 8 meters thick, with fresh-water animals. One 

 alternation. Between arcs 4' and 5'. 



Marne hleue, beds 198 to 204, and Marne blanche, beds 205 to 209, 

 fresh-water marls alternating with marly limestones and ferruginous 

 marls about four or five times. Arc 5' and the first third of arc 6'. 



Marne verte, beds 210 to 217, a brackish-water formation with two al 

 ternations of clay with marl and siliceous limestone. The upper i)a[t 

 of arc 6'. 



Calcaire de Brie, beds 218 to 220, a fresh-water limestone. rerhai)s 

 we have here indications of several climatic alternations, for limestones 

 occur alternating with marl three or four times, though certainly in 

 very thin beds. Its place is in the hollow between arcs 6' and 7'. 



