Continents and Changing Climates
levels rose again during the Eocene, flooding the coastal plains of
Africa, Siberia, and Australia. Uplift of the Rockies ceased toward
the end of the Eocene, but mountain-building continued in Scotland.
The Atlantic Ocean continued widening, and by the middle Eocene an
Arctic channel ran to the North Atlantic and separated North America
from Europe. Faunal interchanges continued between Eurasia and North
America across the Bering land bridge. By the late
Eocene, the collision of the Indian subcontinent with Asia was causing
deformation and mountain-building that would eventually become the
Himalayas. At the end of the Eocene a deep-water connection developed
between the Pacific and the South Atlantic as South America separated
fully from Antarctica.
A brief warming event occurred at the start of the Eocene, as methane
was released from ocean-floor sediments. Over a few tens of thousands
of years global temperatures rose as a result of the methane release,
then cooled again in the succeeding 100,000-200,000 years. Even after
this geologically brief interval of very warm climate, subtropical
climates existed up to relatively high northern latitudes. These areas
had much greater rainfall than today, and less seasonal change in
temperature. Carbonate reefs existed in the Bahamas and from Florida
to North Carolina. From the middle Eocene onward the climate cooled
and became drier. At the end of the epoch circumpolar current formed
in the Southern Ocean because of the northward movement of South America.
The circumpolar current helped to isolate Antarctica and probably
was an important factor in the early development of the South Polar
Ice Cap. The cooling of Antarctica in turn meant that cold water began
to flow north along the ocean bottoms from high southern latitudes.
These changes in ocean circulation brought an end to the long greenhouse
climate that had existed since the Mesozoic.
Eocene Overview |
Terrestrial Life during the Eocene |
Marine Life in the Eocene
Shifting Continents and Changing Climates
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