Re: Large animal extinctions caused by early man

Stephen Barnard (
Fri, 05 Jul 1996 15:53:59 -0800

Scott Barboza wrote:
> Some of the proposed mechanisms for the initiation of the
> Quarternary ice age:
> 1) Positioning of Antarctica over the pole (~50ma)
> 2) Separation of the South America land bridge from Antarctica. This
> allowed circum-polar currents to flow and is probably responsible for the
> flow of Anarctic Bottom Water which began shortly thereafter.
> 3) Iceland volcanism blocked cold water from the vicinity of the North
> Pole from mixing with equatorial waters in the Gulf Stream in the
> Atlantic.
> 4) Subduction-related volcanism along the Aleutian arc blocked cold water
> from the Bering Sea from mixing with equatorial waters in the Pacific.
> I favor a combination of these factors (and probably some that I have
> ommitted). I have heared 1) and 2) put forward the most often and I
> assume that there is some sort of consensus about their role.
> Scott Barboza
> University of Washington
> Department of Geological Sciences

I have heard of a recent theory that the ice age could have been caused
by the solar system passing though a cloud of interstellar dust. That
doesn't seem implausible to me, and it is conceiveably even testable.

Steve Barnard