352 On the Geology of the Baltic. 
tion of a so-great mobility in the crust of the earth actually involves 
a possible fall of the sea also, since a sinking of some great ocean- 
bed would undoubtedly produce a decadence of the surface of the 
ocean, and leave every shore on earth to some extent exposed. For 
my own part, trusting to reason and observation, I shall continue to. 
disclaim an exclusive hypothesis ; prepared to find it ultimately 
ruled that both the sea falls and the land rises, and that a fall of the 
sea to the extent of some thousands of feet, by whatever means brought 
about, was actually one of the last of the great geological events. 
2. A Source of Possible Fallacy regarding the Level of the 
Baltic. 
I had some conversation with Professor Lovén regarding the proofs 
which exist of recent and continued change in the relative level of 
sea and land in Scandinavia. Like all northern men of science, he 
was well aware of the facts bearing upon this subject, and had given 
his accession to the conclusion now generally arrived at, that the 
phenomena depend upon a rise of the land, not a depression of the 
sea. Since Professor Playfair made his famous remark, that a de- 
pression of the sea cannot be of a local nature, while an uprise of 
the land may be so, the superior probability of the latter phenome- 
non has been generally seen and admitted. The conclusion was 
changes its level twice every day, has undergone a permanent depression in 
its surface, than that the land, the terra firma itself, has admitted of an equal 
elevation. In all this, however, we are guided much more by fancy than by 
reason ; for, in order to depress or elevate the absolute level of the sea, by a 
given quantity in any one place, we must depress or elevate it by the same 
quantity over the whole surface of the earth ; whereas no such necessity exists 
with respect to the elevation or depression of the land. To make the sea sub- 
side thirty feet all round the coast of Great Britain, it is necessary to displace 
a body of water thirty feet deep over the whole surface of the ocean. It is evi- 
dent that the simplest hypothesis for explaining those changes of level is, that 
they proceed from the motion, upwards or downwards, of the land itself, and 
not from that of the sea. As no elevation or depression of the sea can take 
place but over the whole, its level cannot be affected by local causes, and is 
probably as little subject to variation as any thing to be met with on the surface 
of the globe.” 
It is evident here thet the learned professor only makes a choice between 
hypotheses with a regard to their comparative simplicity, as accounting for 
phenomena assumedly local. He shews no reason why the sea may not fall and 
rise, though he thinks it less probable than local rises and depressions of the 
earth’s crust. It is on sucha basis that the Hnglish geologists have established 
their conclusion, on which they can endure no breath of scepticism, that there 
can be no change in the level of the sea. A late president of the Society thus 
spoke, in hisannual address in 1847 : ‘ Notwithstanding that this unanswerable 
doctrine was thus clearly laid down so far back as 1802, we still find geologists 
of authority speaking of the sea having risen or fallen, in their endeavours to 
-explain certain phenomena,” &. A very grave delinquency indeed! I must, 
nevertheless, profess my total inability to trace the logic which makes Mr Play- 
fair’s remarks an “ unanswerable doctrine.” 
