144 
THE GROWTH OF CONTINENTS. 
inland soa in the heart of the country. If the 
reader will take the trouble to look on any geo- 
logical map of Europe, he will see an extensive 
patch of Silurian rock in the centre of Sweden 
and Norway. This represents that sheet of wa- 
ter gradually to he filled by the accumulation of 
Silurian deposits and afterwards raised by a later 
disturbance. There is another mass of land far 
to the southeast of this Scandinavian island, 
which we may designate as the Bohemian island, 
for it lies in the region now called Bohemia, 
though it includes, also, a part of Saxony and 
Moravia. The northwest corner of France, that 
promontory which we now call Bretagne, with a 
part of Normandy adjoining it, formed another 
island ; while to the southeast of it lay the cen- 
tral plateau of France. Great Britain was not 
forgotten in this early world ; for a part of the 
Scotch hills, some of the Welsh mountains, and 
a small elevation here and there in Ireland, 
already formed a little archipelago in that region. 
By a most careful analysis of the structure of 
the rocks in these ancient patches of land, tracing 
all the dislocations of strata, all the indications 
of any disturbance of the earth-crust whatsoever, 
Elie do Beaumont has detected and classified four 
systems of upheavals, previous to the Silurian 
epoch, to which he refers these islands in the 
Azoic sea. He has named them the systems of 
