SILURIAN, DEVONIAN, AND CARBONIFEROUS ROCKS NEAR LONDON. 281 
or change of fauna — indeed, all the physical history of the British 
Archipelago — have taken place, on which have been modified the 
shape, size, and life history of the British Islands through all 
time, and by it we have been united countless times to the 
continent of Europe and probably to America. The Irish Sea 
and German Ocean or North Sea, and English Channel are now 
the one a shallow the other a deep hollow in the land, filled by 
the waters of the great Atlantic to the west, their beds being 
only a question of level. 
An elevation of the bed of the German Ocean, or that part of 
the plateau, 100 feet, would unite us again to Europe; and some 
300 or 400 feet would unite England to Ireland, and less than 
half that to France. A depression of one-eighth of a mile, or 
600 feet, would render us an extensive archipelago, when nearly 
all the centre of England would he submerged. The Welsh and 
Cumbrian mountains, the Pennine chain, much of Scotland, and 
the bold coast-line of Ireland, would stand out as islands. The 
Hebrides, Shetland Isles, and those off the west coast of Scot- 
land, are only outliers of the main land, evidences of change, 
mountains in the sea ; the valleys being pasture land and feeding 
ground for dwellers in the ocean, nurseries for the fauna and 
flora of the sea, yet if the bed of the North Atlantic area were 
elevated but a comparatively few fathoms they would no longer 
be islands. It was upon this British and European plateau, 
then a land surface, that our coal growths and coalfields had 
their origin, growth, and development, stretching far away to 
the eastward in Europe, to Mons and Liege, and onwards as far 
as Westphalia, doubtless as one continuous terrestrial surface. 
Movements or oscillations of level through depressions and ele- 
vations greater than the present depth of the Atlantic, did then 
and have since repeatedly occurred, and most if not all the 
phases in the physical history of the British Islands have been 
governed and modified upon this area between the 500 fathom 
level off the western coast of Ireland and the flats of Holland 
and Belgium. 
Such changes are still in action although slow. Unceasingly 
they go on, time only being required to do again all that had been 
done before. The sea, with its tides and ceaseless action, is both 
destroyer and preserver ; it carves and denudes coast lines into 
shape, modifies sea bottoms, and, aided on the land by meteoric 
action through the agencies of rain, frost, ice, wind, and sun- 
shine, fashions into contour the form of the mountain, curves of 
the valley, and depth of the gorge. The creeks of the Australian 
and canons of the American are but terms for phenomena pro- 
duced by rain and river action governed by time. 
The above generalizations tend to lead us to the physiography 
of the older continents and areas, or those of Palaeozoic and 
