Similarity of formbetween subaerial and submarine landscapes aÁected by erosion could suggest
similarities in the process of erosion, such as by runoÁ and sedimentary £ows, respectively. On the
other hand, if aspects of formvary, its characteristics may be used to identify the environmental origin
of erosion.Towards these goals, this contribution addresses the morphology of submarine volcanoes
(seamounts) with widely diÁering histories of erosion. One set from the Paci¢c Ocean never exposed
above sea level includes Cretaceous-age seamounts nearHawaiÕi (including ApuÕupuÕu Seamount),
two seamounts ofo3Ma in age near a mid-ocean ridge and the 11^4Ma Jasper Seamount.These
seamounts are all isolated from continents and hence from any erosion associatedwith mass wasting
of unstable terrigenous deposits. In such isolated submarine environments, surfaces erode slowly
from in situ weathering,mass wasting and scouring by sedimentary £ows initiated by slope failure in
pelagic or bedrock materials.The Paci¢c seamounts are comparedwithValencia Seamount in the
westernMediterranean, exposed subaerially for 100^400 k.y. during theMessinian Salinity Crisis
before 5Ma.Multibeam and deeply towed sidescan sonar data of Valencia Seamount reveal features
typical of subaerial erosion of volcanic islands, such as canyons and relatively uneroded sectors
(planezes) between them.Using a simple topographical reconstruction, the apparent erosion depth
typically reaches 100mwithin canyons and up to 180m in places.Whereas the younger Paci¢c
seamounts do not show these erosional features, the much older Cretaceous seamounts do have
channels, which in one example suggests up to 200m of incision. BothValencia and ApuÕupuÕu
seamounts have channel longitudinal pro¢les that are steep and typically linear to concave upwards.
The erosion depth of ApuÕupuÕu Seamount is signi¢cant, despite the seamountÕs persistent
submarine environment, because of its greater age, steeper £anks and greater contributing areas
to channels compared withValencia Seamount.These results illustrate that the channel morphology
resulting from submarine erosion can become similar to that produced by subaerial erosion given
suÚcient time.
Mitchell, NC and J Lofi, Submarine and subaerial erosion of volcanic landscapes: comparing Pacific Ocean seamounts with Valencia Seamount, exposed during the Messinian Salinity Crisis, Basin Research, in press. 10.1111/j.1365-2117.2008.00355.x