:x.] ON A PIECE OF CHALK. 175 



Yorkshire — a distance of over 280 miles as the crow 

 flies. 



From this band to the North Sea, on the east, and the 

 Channel, on the south, the chalk is largely hidden by 

 other deposits ; but, except in the Weald of Kent and 

 Sussex, it enters into the very foundation of all the 

 south-eastern counties. 



Attaining, as it does in some places, a thickness of 

 more than a thousand feet, the English chalk must be 

 admitted to be a mass of considerable magnitude. 

 Nevertheless, it covers but an insignificant portion of 

 the whole area occupied by the chalk formation of the 

 globe, which has precisely the same general characters 

 as ours, and is found in detached patches, some less, 

 and others more extensive, than the English. 



Chalk occurs in north-west Ireland ; it stretches over 

 a large part of France, — the chalk which underlies Paris 

 being, in fact, a continuation of that of the London 

 basin ; it runs through Denmark and Central Europe, and 

 extends southward to North Africa ; while eastward, it 

 appears in the Crimea and in Syria, and may be traced 

 as far as the shores of the Sea of Aral, in Central Asia. 



If all the points at which true chalk occurs were 

 circumscribed, they would lie within an irrregular oval 

 about 3,000 miles in long diameter — the area of which 

 would be as great as that of Europe, and would many 

 times exceed that of the largest existing inland sea — 

 the Mediterranean. 



Thus the chalk is no unimportant element in the 

 masonry of the earth's crust, and it impresses a peculiar 

 stamp, varying with the conditions to which it is 

 exposed, on the scenery of the districts in which it 

 occurs. The undulating downs and rounded coombs, 

 covered with sweet-grassed turf, of our inland chalk 

 eountry, have a peacefully domestic and mutton- 



