William Atkins
Wednesday, 21 January 2009 22:30
Science -
Biology
Page 2 of 3
The French and Australian researchers state,
“… we investigate the continental freeboard predicted using
different models for the cooling of the Earth.”
Continental freeboard
is defined as the average level of the surface of the sea relative to
the continents.
In fact, they show through their mathematical models that the mantle of
the Earth was 110 to 210 degrees (Celsius) hotter than what it is
today, primarily due to more abundant radioactive elements being
present.
Radioactive elements, such as uranium, decay over time, and in
the process produce heat. At that time, heat flow from the mantle to
the crust was about three times higher than it is today.
The extra heat would have made the continental crust hotter than today
and, thus, more thick than it is today.
With the continental crust
laying the foundation of the Earth’s oceans, a thicker crust would have
meant the bottom of the oceans were higher then than they are now.
The researchers state,
“We show that constancy of the continental
freeboard (± 200 m) is possible throughout the history of the planet as
long as the potential temperature of the upper mantle was never more
than 110–210 C hotter than present. Such numbers imply either a very
limited cooling of the planet or, most likely, a change in continental
freeboard since the Archaean.”
Page three defines the Archaeon period, along with stating what happened to Earth after land began to appear from beneath the oceans far away.
