THE MEDITERRANEAN NATURALIST 
159 
cliff-faces and rock-surfaces, have been influenced 
by the lithological characters of the rock. These 
are some of the assistants that have co-operated, 
add to which the heat and drought of summer, and 
the wet and cold of winter. 
But effective as they are as helpers in the work 
of waste, no single one of them can be pointed to 
as being more potent, more active, more irresistible 
than the sirocco. 
Both in Malta and Gozo the principal valleys 
lay in a north-west and a south-east direction; that 
is to say, they lie in a line with the direction of 
this wind. 
Marsa Sirocco, an extensive bay on the east coast 
of Malta, so called because this wind blows directly 
into it, affords many striking examples of its 
power. It is the largest bay in the islands, and 
has four valleys abutting on its coast-line, each of 
which lies in the same direction. But it is not 
only in the general moulding of the country that 
the sirocco is concerned. Its effects may be traced 
in every crag and cavern, and on every rock, 
boulder, or other rock-surface. The irregular 
blocks of which the walls that serve as boundary- 
partitions between the fields, and the tooled stones 
of which the edifices in the towns and casals are 
built afford equally striking evidences of its 
power of erosion; and by their means both the rate 
and the amount of the denudation may by estimat- 
ed. It is a noteworthy feature in the exteriors of 
Maltese walls and houses that the side which is 
exposed to the sirocco always presents a very 
eroded, time-worn and dilapidated appearance, 
whereas the other sides, in comparison, are fresh 
and unworn. 
It is no uncommon occurrence to find the softer 
stones in the sides of the houses that have a south- 
east aspect, almost completely worn through, and 
surrounded by other blocks, the harder portions of 
which, such as the fossil contents, echinoids, 
pectens, etc., stand out in bold relief from their 
worn and wasted matrices. In the old fortifica- 
tions that were erected by the Knights of St. John, 
such phenomena as these are of frequent occur- 
rence, and are very typical of sirocco denudation. 
From a series of calculations that I have made 
of the rate of the erosion of the Globigerina 
Limestone blocks in a number of buildings and 
fortifications of known ages, I estimate that the 
rate of sirocco denudation averages of an inch 
per square foot per year; that is about 16 cubic 
yards per acre per year; or about 22 tons of 
material are annually wasted from every acre of 
surface. 
In calculating this, numerous examples were 
' taken, some being in proximity to the coast, while 
others were obtained from the centres of both 
islands. By so doing I believe i have obtained a 
fair average rate, for there can be no doubt, but 
that the rate of erosion is more rapid near the 
coast than it is inland. The moisture-ladened 
winds that sweep over the islands impregnate all 
that they come in contact with, and the Globige- 
rina rock being very porous, is therefore highly 
susceptible to its influence. 
The duration of time during which the sirocco 
lasts is seldom long enough to enable it to do 
more than affect the surface, and the period of 
moisture is usually followed by conditions that 
are diametrically opposed to those that prevailed 
while the sirocco was blowing. 
The frequent and rapid changes that the stone 
thus undergoes, causes an abnormal expansion 
and contraction of the superficial molecules, and 
so tends to make the surfaces readily disintegrate 
and peel off in large flakes. 
The work of erosion is greatly assisted also by 
the crystalization of the salt contained in the 
moisture that this wind takes up in its passage 
across the Mediterranean. 
This moisture renders the stone surfaces highly 
saliferous. Under the influence of the heat of a 
semitropical sun, the moisture passes off, and the 
salt crystallizes and pushes out the superficial 
particles of the limestone, thus facilitating the 
paring down process which so rapidly wastes the 
rocks, and causes them to break up. 
Johx H. Cooke. 
Deep-Sea Explorations in the Eastern 
Mediterranean. 
The deep-sea explorations in the Eastern parts 
of the Mediterranean, which were continued this 
year by the Austrian Government, on board the 
Pola, were rich in interesting results; they are 
analysed by Prof. J. Luksch in the Sitzungsberichte 
of the Vienna Academy (vol. 100, 2nd division), 
and were briefly referred to in the ‘Proceedings’ 
