----------------------------------------------------------------------
The Learning Kingdom's Cool Fact of the Day for September 29, 1999
----------------------------------------------------------------------
How do scientists read Earth's prehistoric climate?
----------------------------------------------------------------------
By drilling down through layers of undisturbed sediment or ice with a
hollow drill bit, scientists can obtain cores up to several
kilometers long that contain information about Earth's climate in
past millennia.
Sediment cores from deep lakes contain spores and pollen. Cores of
ice from glaciers and ice sheets contain trapped bubbles of ancient
air. Cores of ocean sediments contain the shells of plankton, plus
layers of dust and clay.
Pollen grains reveal the species of plants living nearby. Plankton
shells reveal ocean temperature. Air bubbles in ancient ice reveal
the concentrations of carbon dioxide and methane. By combining the
data from many cores, we can build a long climatic history, reaching
millions of years into the past.
The longest ice core ever obtained, from Vostok Station, Antarctica:
http://www.agu.org/sci_soc/vostok.html
Sediment cores provide evidence about the extinction of the dinosaurs:
http://www.accessexcellence.org/WN/SUA08/ext996.html
http://www-geology.ucdavis.edu/~GEL107/KT.html
Today's sponsor: Cybergold
"Click Here to Join Cybergold -- the Internet's premier incentive
program. Cybergold pays you REAL CASH to read ads, complete
surveys and make purchases on the World Wide Web. Become a
member and "Get Paid to Surf the Web" today. It's FREE!"
http://www.cybergold.com/pid/500200001094_txt_001
----------------------------------------------------------------------
Cool Fact of the Day list membership: 174,758
----------------------------------------------------------------------
To send a free gift subscription: http://www.tlk-lists.com/giftsub/
Subscribing, unsubscribing, address changes:
Existing subscribers: http://www.tlk-lists.com/change/
To join as a new subscriber: http://www.tlk-lists.com/join/
To become a sponsor: http://www.tlk-lists.com/sponsor/
Feedback: [EMAIL PROTECTED]
----------------------------------------------------------------------
Copyright (c) 1999, The Learning Kingdom, Inc.
http://www.LearningKingdom.com
----------------------------------------------------------------------
