1893. ARE OCEAN DEPTHS PERMANENT? 183 
from the European continent. And all this varied new-born land 
would be green and full of life, and people would not be at all willing 
to believe that it ever was not so. 
Then we would descend to the new shore, and one of our great 
masters would tell us that ocean depths are permanent, that is to say, 
from 1,500 fathoms downward, or from 2,000 fathoms. The general 
impression resulting from the study would be the same as now, but 
the assumed permanent level would be reduced by 500 fathoms. 
We might invite our master to undertake an excursion with us; 
we would go to Scotland. An isthmus, some 1,200 feet high at the 
narrowest part—Sir Wyville Thomson’s ridge—would lead us first to 
some isolated peaks, nearly 3,000 feet high, and over a rising country 
to the high peaks of the Farées. We would observe land-born coal- 
beds between the great coulées of basalt. Proceeding further, we 
would travel to the north-west, over a broad tract of rocky land some 
1,200 or 1,300 feet high; then first meet an isolated mountain of 
about 1,800 feet, and from there ascend to the volcanic mass of 
Iceland, where we should see those vast fields of lava, dotted 
with active volcanoes, and observe the long faults and open rents 
cutting through the masses of lava and trending across Iceland ina 
broad arch, first from south-west to north-east, then northward, 
beyond the volcano Askja to Husavik; and beyond this broken and 
breaking zone we might gain the great ‘‘ effondrement ” or ‘“‘ Kessel- 
bruch ” of Faxafjord, beset all round by volcanoes and hot springs, 
from Snaefells Jokull to Reykjavik. In following the rents so well 
described by our indefatigable Thoroddsen, we might detect faulted 
plant-bearing beds, and recognise the equivalents of the Farée coal- 
seams. If some younger and more impressible student be in our 
company he might well exclaim, in face of these plant-bearing beds, 
stretching on to Greenland and showing the existence of a vast dry 
land in late times, and in face of these rents and volcanoes: “ Verily, 
Professor, the sagging-down of the North Atlantic is the most recent 
event ; it is going on before our eyes; and as the highest mountain 
chains are the youngest, so also are the deepest parts of the planet the 
most recent.” I fear I should not know how else to answer the student 
than, ‘“‘ Really, I do not know.” 
Now let us quit the coasts and examine the interior of a great 
continent. 
Modern geology permits us to follow the first outlines of the 
history of a great ocean which once stretched across part of Eurasia. 
The folded and crumpled deposits of this ocean stand forth to heaven 
in Thibet, Himalaya, and the Alps. This ocean we designate by the 
name ‘‘ Tethys,” after the sister and consort of Oceanus. The latest 
successor of the Tethyan Sea is the present Mediterranean. 
I asked Dr. Diener, recently returned from India, to give me his 
estimate of the thickness of the deposits in the Silakank region. Dr. 
Diener answers: From Dhauli-Ganga Valley, between Gweldung 
