298 PICTUKESQUE SKETCHES 



matter. The picturesque basaltic columns of the 

 Giant's Causeway and Staffa mark the extent and 

 intensity of a line of volcanic action, which has long 

 ceased to produce direct results in the British islands. 



After the lapse of a certain period, and when the 

 elevatory movements had long gone on, the continent 

 of Europe was at length fully brought above the 

 surface of the sea, and became a fit habitation for 

 the land animals of various kinds gradually intro- 

 duced upon it. The deep and broad inlets of the sea 

 became valleys and plains ; the lakes were drained by 

 the great river channels, which, owing to the greater 

 elevation of the interior, conveyed the water in a de- 

 finite and short course to the sea, instead of allowing 

 it to stagnate over wide tracts of low swampy land ; 

 and the whole Continent put on its present aspect. 



But during these changes the climate had also 

 become greatly modified. The increased proportion 

 of land, especially towards the north, would neces- 

 sarily lower the general temperature, and at the 

 same time render the climate more excessive. Vast 

 forests, composed of oak and beech and other mo- 

 dern trees, produced other arid not unimportant mo- 

 difications ; and at this period, probably before the 

 great expanse of land towards the North Pole had 

 arisen from the sea, and while the general character 

 of the great European tract was still insular, vegeta- 

 tion extended almost to the Arctic Circle, and to 

 such an extent as to provide food and shelter for the 

 largest quadrupeds. This combination of analogies 

 and differences forms throughout a somewhat striking 

 character of the middle period, and we find, as one 

 result, that the physiognomy of the fauna at pre- 



