TERTIARY COAL. 
139 
of the insects now fixed in their ebon ca¬ 
binet here, are similar to those which now 
flit over the plains of Provence ; and the 
seed vessel of the chara^—the common 
weed of our little pools, denotes a compara¬ 
tively recent origin for these deposits. The 
beautiful preservation of the insects, their 
lace-like wings and burnished armour in so 
rude a museum, is truly wonderful. 
On the south eastern slope of Dartmoor, 
there is a large deposit of lignite at Bovey, 
called Bovey Coal, referrible also to the 
tertiary era. 
One of the most remarkable of these 
mimic coal fields is displayed amidst the 
snows of Iceland. A substance called sur- 
turhrand, consisting of bituminized wood, 
occurs in regular subterranean layers 
throughout the whole of the north-western 
peninsula of that Island. It is used for the 
smithy, and in the manufacture of orna¬ 
mental articles of household furniture. 
The mode of its occurrence presents us 
with a forcible representation of the an¬ 
cient forests growing in high northern 
latitudes on the volcanic slopes of that 
