be apt to be maritime; but why volcanoes
should cling to the rising edge of the cracks I cannot conjecture. That
areas with extinct volcanic archipelagoes may subside to any extent I do
not doubt.

Your view of the bottom of Atlantic long sinking with continued volcanic
outbursts and local elevations at Madeira, Canaries, etc., grates (but
of course I do not know how complex the phenomena are which are thus
explained) against my judgment; my general ideas strongly lead me to
believe in elevatory movements being widely extended. One ought, I
think, never to forget that when a volcano is in action we have distinct
proof of an action from within outwards. Nor should we forget, as I
believe follows from Hopkins (489/2. "Researches in Physical Geology,"
W. Hopkins, "Trans. Phil. Soc. Cambridge," Volume VI., 1838. See also
"Report on the Geological Theories of Elevation and Earthquakes," W.
Hopkins, "Brit. Assoc. Rep." page 33, 1847 (Oxford meeting).), and as I
have insisted in my Earthquake paper, that volcanoes and mountain chains
are mere accidents resulting from the elevation of an area, and as
mountain chains are generally long, so should I view areas of elevation
as generally large. (489/3. "On the Connexion of certain Volcanic
Phenomena in S. America, and on the Formation of Mountain Chains and
Volcanoes, as the Effect of the same Power by which Continents are
Elevated," "Trans. Geol. Soc." Volume V., page 601, 1840. "Bearing in
mind Mr. Hopkins' demonstration, if there be considerable elevation
there must be fissures, and, if fissures, almost certainly unequal
upheaval, or subsequent sinking down, the argument may be finally
thus put: mountain chains are the effects of continental elevations;
continental elevations and the eruptive force of volcanoes are due to
one great motive, now in progressive action..." (loc. cit., page 629).)

Your old original view that great oceans must be sinking areas, from
there being causes making land and yet there being little land, has
always struck me till lately as very good. But in some degree this
starts from the assumption that within periods of which we know anything
there was either a continent in such areas, or at least a sea-bottom of
not extreme depth.

LETTER 490. TO C. LYELL. King's Head Hotel, Sandown, Isle of Wight, July
18th [1858].

I write merely to thank you for the abstract of the Etna paper. (490/1.
"On the Structure of Lavas which have Consolidated on Steep S