SCIENTIFIC CONGRESS OF FRANCE. 
4a 
the masSj until it meets with a new surface, where it stops ; 
which at once proves the difference of the glacier from common 
ice. 
5. On the Geology of the environs of Niederhronn ; by M. En- 
GELHART. 
This district of lower Alsace is thus constituted: — 1. The 
triassic series of Alberti, resting on the Vosges. 2. The Jurassic 
series, more or less complete. 3. The so called Molasse^, of 
considerable thickness in some parts. 4. The marsh and silt 
of Bouxwiller, only traceable in a few patches, being covered in 
most instances by diluvium and alluvial formations. 5. Loess. 
— An accumulation of lime, clay and gravel, of a dirty yellowish 
grey colour, and containing grains of mica. The profile of Nie- 
derhronn to the extent of 2 leagues, embraces the Syenite of 
Jaegerthal, the sandstone of the Vosges {gres vosgienj and the 
triassic series, the beds of which are much dislocated by dis- 
turbances subsequent to the upheaval of the Vosges. The keuper 
fmarnes iriseesj are but imperfectly developed in lower Alsace. 
The calcareous grit or lias sandstone, which, in the neighbour- 
hood of Oberbronn, covers the marls of the keuper series, incloses 
the same fossils as the calcareous grit of Lorraine and Luxem- 
bourg. The lias then succeeds, and is divisible into three por- 
tions: — 1. The great lias bed, characterized by the Ghyph(jea 
arcuata, Plagiostoma giganteum, P. Hermanni, Ammonites Buck- 
landiij A. Conyheari^, (the lias marl abounds in Avicula inequi- 
valvis. 2. A bed of lias marl, which includes numerous ammo- 
nites, teeth and bones of fish, and Astarte Voltzii, Nucula Her- 
manni, Gryphcea ohliqua^ and other interesting fossils. 3. The 
upper bed distinguished by numerous Ammonites primordialis, 
and Trigonia navisj so common at Gundershofen. 
* A sandstone of granular texture, named by French Geologists, " gres-tertiaire 
a lignites." 
* These two fossils, and the Gryphasa, Avicula, and Plagiostoma are abundant in 
the lias beds of this country. 
g2 
