Geology Reference
In-Depth Information
intospace,thenEarthwillsurelybetreasuredasneverbefore—asapreserve,asamuseum,
as a shrine and place of pilgrimage. Perhaps only by leaving our world will humans ever
fully appreciate the place of our species's birth.
Earth's Changing Map: The Next Million Years
In many respects, Earth a million years from now will not have changed very much. The
continentswillhaveshifted,tobesure,butprobablynomorethanthirtyorfortymilesfrom
theirpresentrelativelocations.TheSunwillstillshine,risingeverytwenty-fourhours,and
the Moon will still orbit once every month or so.
But some things will have changed a lot. In many places around the globe, inexorable
geological processes will have transformed the landscape. The most obvious changes will
affect vulnerable coastlines. One of my favorite places, Calvert County, Maryland, with its
miles of fast-eroding Miocene Epoch cliffs and their seemingly limitless store of fossils,
willhavedisappearedcompletely.Afterall,thecountyisonlyfivemileswide,andit'sget-
ting skinnier by almost a foot a year. At that rate, Calvert County won't last fifty thousand
years, much less a million.
Inotherstates,geologicalprocesseswilladdvaluablenewrealestate.Anewocean-floor
volcano off the southeastern coast of Hawaii's big island is already almost two miles high
(though still submerged) and growing larger every year. A million years from now a new
island, already named Loihi, will have risen from beneath the waves. Of course, older ex-
tinct volcanic islands to the northwest, including Maui, Oahu, and Kauai, will become cor-
respondingly smaller as wind and waves erode them away.
Speaking of waves, scientists who examine the rock record for hints of what is to come
concludethatEarth'sgeographywillbealteredmostdramatically bytheadvancingandre-
ceding oceans. Changes in the rate of rift volcanism have a long-term effect, as greater or
lesser volumes of lava solidify on the ocean floor. Sea level can drop significantly during
lulls in ocean volcanism, when seafloor rocks cool and settle, as many suspect occurred
during the dramatic fall of sea level just before the late Mesozoic extinction. The presence
or absence of large inland seas like the Mediterranean and the assembly and breakup of
continents cause major changes in the extent of shallow coastal waters, which play yet an-
other important role in the shape the geosphere and biosphere will take in the next million
years.
A million years corresponds to tens of thousands of human generations—hundreds of
times all of recorded human history. If we survive, then Earth may be physically trans-
formed by our evolving technological prowess in ways we cannot easily imagine. But if
we die out, Earth will likely soldier on much as it is today. Life on land and in the sea will
