488 
GEOLOGICAL FEATURES OF OUR GLOBE. 
may be of sufficient power to cause temporary disturbance 
and ruin. The fact that meteoric bodies do fall on our earth 
suggests the possibility of larger ones haying fallen or passed 
sufficiently near as temporarily to disarrange or even alter 
its law of revolution. 
The gradual retiring of tbe waters from the surface of the 
earth has led to its improved temperature ; a large portion 
of the great desert of Sahara is stated to be below the level 
of the ocean^ and in common with similar sandy deserts leads 
to the supposition of their being desiccated sea beds, these 
now add greatly to the heat not only of the neighbouring 
countries; but even of others afar off; the radiation of heat in 
those sandy wastes affect the temperature of a large portion 
of Europe. The Sirocco is known in Switzerland as the 
Fohn; or pestilential wind; but however justly so called it is 
still beneficial in ameliorating the climate in general. In 
a similar way the hot winds of Central Australia sweep over 
the southern portion of New Zealand; and raise the tempera- 
ture of its climate. 
The greater extent of land in the northern hemisphere to 
to that of the southern; has also been the cause of a remark- 
able climatic difference between the two ; extremes of heat 
and cold distinguishing the one; and the absence of them 
the other. The gulf stream not only greatly improves the 
climate of lands; which otherwise from their geographical 
position; would have had a more glacial character; but has 
also effected great local changes ; the force of its current; 
which is now scooping the Bay of Biscay; in former times 
was most probably the grand agent in sweeping away the 
Isthmus; which connected Britain with the continent; and 
thus raised the sea level of the German Ocean; inundating 
the low lands on both sides; and forming fens; where before 
there were fertile and cultivated districts on the east coast 
of England; and in Holland; whilst at the same time; the 
sudden withdrawal of a vast body of water from the south 
side of the Isle of Wight would naturally cause a grand 
subsidence of its coast; which formed a cliff several hundred 
feet high; and gave Yentnor its superior climate; by the shelter 
it thus acquired from the cold winds of the north. 
