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Re: Chesapeake Bay Crater

> The Chesapeake Bay impact is one of several major impacts that occurred
> close together in time near the Eocene/Oligocene border. It has been
> hypotesized that these could be related and due to a "comet swarm"

Which are the others? Popigay and... ?

> The climate shift
> probably had paleogeographic causes, Australia became well separated from
> Antarctica opening a circum-Antarctic ocean which climatologically
> Antarctica, probably causing the first widespread glaciation there.

South America, not Australia. AFAIK Australia broke off 45 million years
ago, and Eastern Antarctica already iced over then. The circumpolar cold
current became established when the land bridge between South America and
Western Antarctica broke; at this time all of Antarctica froze, and
worldwide temperatures and sea levels began to drop.

> There
> were other major geographic shifts att approximately the same time, for
> example Europe which had long been an archipelago with connections with
> North America earlier inthe Eocene became connected with Asia instead.

Have the dating problems been solved in the meantime? AFAIK nobody knows
whether the extinctions were coeval with one another, the impacts, the
geographic changes and the climate shifts...