772 Excursions of the Geological Soc. France, 1878. [December, 
named locality, a beautiful section of the Lower Eocene or 
Suessonien was examined, which displayed principally the 
Argile Plastique, below the thin beds of the Lignite of the 
Coryphodon, Gastornis and Palgonyctis. The whole was crowned 
by massive beds of the Calcaire Grossier of the Middle Eocene, 
with its numerous invertebrate fossils. I viewed these exposures 
with great interest, as the formations contain the remains of a 
fauna which I rediscovered in New Mexico in 1874. By this 
discovery I was able to identify the Wasatch horizon of the 
Rocky mountains with the Suessonien, thus establishing a basis 
for comparison of formations above and below it, a want nota 
little felt in North American paleontology. But how different 
the petrography of the Paris basin from that of North-western 
ew Mexico. Here a thick bed of tenacious lead-colored clay 
_ 18 surmounted by a stratum of more or less impure lignite; in 
New Mexico heavy beds of hard sandstone alternate with still 
thicker red and yellow strata of arenaceous marl. 
The Calcaire Grossier here yielded its numerous Echint, Cardita 
planicosta, Nautilus, etc. Further on, along the road towards 
Meudon, its softer beds formed the banks on either side. Here 
they were almost composed of two species of Nummulites, N- 
levigata and N. lamarckii. Still beyond we visited one of the 
quarries whence had been obtained many huge blocks of the soft 
limestone from which so large a part of the city of Paris has been 
built, and to whose yielding qualities so much of the architectu- 
ral beauty of the Capital of France is due. Here some of the 
desolating effects of the German siege were still to be observed. 
The lowest Suessonien, the Marnes Strontianiferes with their 
curious mixture of the marine and fresh water shells of the Cal- 
caire Grossier and sands of Rilly, recently discovered, were 
passed as a white bank on the side of the public way. At Meu- 
don the upper beds of the Cretaceous came in view. The con- 
tact of the Pisolitique (Mestrichtien or Fox hills) with the 
Marnes Strontianiferes above, was noted as the point of separa- 
tion between the Tertiary and Cretaceous series. The situation 
is as though the Wasatch rested immediately on the Fox Hills 
beds, without the intervention of the great Laramie series ; 
although the Marnes must be regarded as lower in the scale than 
the lowest Wasatch yet found in North America. A fine expo- 
_ sure of the Chalk, with its characteristic fossils, succeeds the Piso- 
x 
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