8 'THE MEDITERRANEAN NATURALIST 
a .nd the cliffs are, therefore., no more than 20 feet 
tigh in some parts, while, towards the west, the 
strata shelve gradually off and finally disappear in 
the sea. 
At the mouth of the bay there is an outlier of 
the Lower Coralline Limestone, which is known 
as the Fungus or General’s Rock. 
It was once, apparently, a continuation of the 
now depressed northern boundary. 
The bay itself forms the embouchure of the 
Dueira valley, the catchment area of which Is 
bounded on either side by a fault of considerable 
magnitude. That on the northern side extends 
from the General’s Rock to the northern base of 
the hill known as Ghar-Ilma. The down-throw j 
that has resulted from this fracture has depressed 
the area to the south of it to about 40 feet below 
the top surface of the Lower Limestone escarp 
meat, which lies exposed along the line of fault. 
The fault on the southern side of the bay 
extends from Dueira, via Monsciar to Miggiar 
Scini, and the result of its fracture has been to 
depress the area to the north of its line. The 
accompanying map will show the relative posi- 
tions of these two faults, and the efFec they have 
had on the area that lies between them. 
The strata, that have thus been let down, are 
much broken and displaced; and, on the southern 
slope especially, there are several minor faults all 
of which trend in a direction that is at right angles 
to the main fracture. 
The beds on both sides of the valley slope at 
varying angles, in many cases the inclination 
being as much as 45° and even 60° out of the 
horizontal. 
The beds dip inwards; and the result of the 
synclinal, which lias thus been formed, is the 
Duera valley, the bed of which is represented by 
the trough of the syncline. 
The southern slopes are very uniform in outline; 
but those on the northern sides are divided into a 
series of smaller valleys or gullies, down which 
miniature torrents pour their waters for a few 
occasional hours in the winter time. 
The deposits of which the sides of the valley are 
composed do not consist of the Lower Coralline 
Limestone (Bed V) as is represented in the geolo- 
gical map of the Island, which was published by 
Ducie, Spratt, Adams, and Murray. 
The Lower Limestone is entirely absent save 
bound the valley. 
The bed and sides consist of representatives of 
all of the formations that are to be found interstra- 
tified between the Upper and Lower Coralline 
Limestones in other parts of the island viz. the 
Globigerina Limestone, the Marl and the Green- 
sands. 
The Globigerina bed is the predominant rock; 
but both the blue and yellow clays and the Green- 
sands are found in abundance along the Southern 
slopes. 
Fringing the upper portion of the sides of the 
valley the Lower Limestone may be seen marking 
the line of fault with the Globigerina beds of the 
undisturbed district above, and those of the 
depressed area beneath it. 
The former relation that existed between the 
depressed area and its surroundings is therefore 
distinctly apparent. 
I have entered thus into detail because some 
misapprehension appears to have formerly existed 
with reference to the geology of this part of the 
island. Instead of being a valley of erosion simi- 
lar to the Kaura, Scini, Sclendi, Asel, and Zebbug 
gorges, it is simply a depressed area, wdiich has 
been let down bv the dislocation of the strata on 
either side of it. 
It is also important that these details should be 
carefully noted, as on their correct representation 
depends the proofs that much be adduced for 
proving the relationship which formerly existed 
between the Pleistocene deposits found in the 
valley below the line of fault, and those found on 
the summit of the slopes above it. 
It was while engaged in noting the points of 
difference between the geology of the district as it 
is represented on Ducie’s map, and that which 
actually exists, that I first came across the Pleisto- 
cene bed which I am about to describe. 
Starting at the head of the valley and proceed 
ing towards its mouth, the Globigerina strata will 
be seen sloping down the valley side, at angles of 
varying magnitude, and breaking off abruptly 
towards the lower edge they form cliffs of trom 
