THE MEDITERRANEAN NATURALIST 
On the Miocene Beds of Western Algeria. 
BY 
Prof. Juf,j3§ Welsch. 
The Miocene stages are to be seen in the normal 
order of succession near Hamman Kira, a depart- 
ment of Algeria, where they are superimposed on 
the Cretacious. The following order may there be 
observed, commencing from the base: — 
I. Lower Miocene (Miocene inferieur). — Con- 
glomerates and limestones from the Djebel 
LJienansolla to the bridge of Djer chez Granger, 
surmounted by grey marls. 
These I refer to the Langhien stage, or Miocene 
inferieur as it is now called. 
IL Middle Miocene. This is made up of two 
formations the lower of which consists of sand- 
stones, and limestones containing Lithotham- 
nium, Heteroster/ines, and numerous Glypea&ters. 
It is a sub-eorralline formation, of very variable 
thickness sometimes thinning out to a few meters 
as at Moula where I found a rich bed of Cly- 
peaste/rs of the Middle Miocene. The second 
stratum is formed of blue and grey argillaceous 
clays which attain several hundreds of meters in 
thickness in the Bon Allouance. In its upper 
part intercalated deposits of sands and sands- 
tones occur, containing typical Ostreci crassisima. 
These two beds represent the Helvetian stage 
of European geologists. 
III. Upper Miocene. This is represented by sand 
stones and yellow sands overlaid by pebble beds 
from Gontas to Ohelif. This I shall show show 
further on is the Tortonian stage. 
In following the coast of this Miocene area to 
the west of Hamman Bira in the direction of 
Adcleiaand Miliana the lower stages (Langhien) 
are to be seen passing laterally into pebble beds 
and sxndstones'of a peculiar greenish brown colour 
and having a remarkable sandstone facies. This 
has been called the etage cartennien by.M. Pomal. 
1 have found a somewhat large variety of Ostreci 
traxsisxima in it, on the old telegraph road to 
Adelia. It is identical with the specimens that I 
have found in the Helvetian stage. I may add 
that the characteristic features of the Cartennien 
301 
stage are often found developed in the Middle 
Helvetian. 
To the east of the Hamman Birr basin a similar 
change of the general facies of the rocks of the 
mountains of Soumata and of Mouzaia is also 
noticeable. On the road to the Mouzaia Pass 
beyond Ain Ismat the Langhian and Helvetian 
beds are also to be seen. The Helvetian often lies 
immediately on the more ancient strata, and in 
this case the lower bed containing the Gh/peasters 
is after found to be no more than one meter in 
thickness, and sometimes it is entirely 'wanting, 
If these strata be followed to the west of Algeria, 
to the north of the lofty mountains of Ouarseusis 
and through the valley of Chelif, they will be 
found to be fossiliferous to the north of Carnot and 
towards Beni Bached. 
The sections in the Boukali basin exhibit the 
following order. 
2. The Helvetian stage is frequently found rest- 
ing upon the Cretacious, and includes very thick 
grey clays, and marly sandstones. 
Facilities for the study of these are offered 
along the new road to Dainous. 
3. Above these are found sandy clays, containing 
Tortonian fossils: Ancillaria gland if onrtis , Tier- 
ritella valriacensis, and numerous varieties. 7'ur- 
ritella archimechs , Pleurotoma ramosa, Pl'evroto- 
m r i cataphracta , Carclita Jonanneti, Area 
diluvii., etc. etc. 
These fossil beds are overlain by sands and 
yellow sandstones, and by pebble beds which 
mark the limits of the Upper Miocene. I did 
not find any fossils there. 
III. If the Miocene Beds be traced through the 
province of Oran from the southern side of 
Ouarseusis towards Tiaret and Mascara, the 
the Helvetian strata will be often be found 
resting directly upon Jurassic and Cretaceous 
formations. 
Near Marcara a similar order of succession m 
that which I have just mentioned may be 
observed. 
2. At the base in the ravines of Sidi Aiiiar, to 
the the right of the road leading to Orw near 
91st miistone, beeds of the and coase sandstones 
pebblesare to be seen which probably represent 
the Lower Helvetian. The Helvetian is generally 
