MAECOU OX THE XEOCOMIAN AXD THE WEALDEX ROCKS. 5 



(c). The Neuchatel stone, or yellow stone {Pierre jaune ou Pierre de 

 Xeuchatel), sixty feet thick, is the beautiful material which gives to 

 the buildings of the town of Xeuchatel that clear yellow colour so 

 much admired by trayellers. Fossils are rare in this division, and 

 never in a good state of preservation. Typical localities : vicinity of 

 Neuchatel and Pontarlier. 



The Upper Neocomian, or Xoirvaux, group is well developed in the 

 ISToirvaux valley near St. Croix j it is this group, or rather the 

 fauna contained in its strata, that D'Orbigny has called Urgonian. 

 Two divisions are generally found in it j (a) the Mauremont rocks, 

 and (h) the Noirvaux-Dessus Limestone. 



{a). The Mauremont rocks {Roches du Mauremont)^ forty feet thick, 

 consist of yellow limestone, very difficult to distinguish from the divi- 

 sion below ; they become marly, and finally terminate with a bed of 

 yellow marls containing numerous fossils. The characteristic fossils 

 are : Janira atava, D'Orb. ; Toxaster Couloni, Camp, j Pygurus pro- 

 ductus, Agass. ; Cidxiris clunifera^ Agass. ; Caprotina Dubuisiij Mer. ; 

 Rhynchonella lata, D'Orb., ka. Typical localities : Mauremont in 

 the Canton de Vaud ; St. Croix, Travers, Bole, (fee. 



(6). The Noirvaux-Dessus Limestone {Calcaires de Xoirvaux-Dessus), 

 one hundred and ten feet thick, has been often called the Caprotine 

 Limestone ; it is a series of beautiful white and sometimes yellow 

 limestones, affording a marble much employed at Thoiry, near Geneva. 

 Characteristic fossils ; Caprotina ammonia, D'Orb., and Radiolites Neoco- 

 miensis, D'Orb. Typical localities : Noirvaux-Dessus, near St. Croix, 

 Thoiry, Les Rousses, (fee." 



The strata of the Greensand formation lie directly above the 

 Neocomian and in concordance of stratification. Eugene Renevier, 

 who has made a special and very successful study of the Greensands 

 in England and at the Perte du Rhone, considers the lower Perna- 

 bed, containing the Natica roiumlata, Sow., (fee, of the Lower Green- 

 sand of the Isle of Wight, to be the equivalent of the yellow clay 

 {Marnes jaunes) containing Xatica rotunda.ia, Sow., (fee, of his 

 Rhodanian gTOup of the Greensands of the Perte du Rhone. 



* For a more detailed accoimt of the Xeocornian Strata, see Bur U Neocomien 

 dans le Jura et son rdle dans la. serie st-ratigrajjhique, by Jules ]Marcou. 

 Geneve, 1859. 



