I would strongly suggest asking your friendly local geology department - they are far more likely to have good answers than any published map will carry, as it is a very active research field. Definitive answers are probably not available, but the list in the email is definitiely wrong, by quite a lot (Juan de Fuca Plate, Nazca Plate amongst many others). The further we go into the past, the less confident we can be of the number of plates - indeed, the only confident statement we can know is that we don't know them all! To give a present day point of contention, we are not certain how many micro plates have made up west Antarctica in the recent past, and I suspect that any two Antarctic geologists will give you three or more answers!
Good luck
Paul Cooper
<<< Francis Herbert <[log in to unmask]> 11/16 9:51a >>>
Dear Lis-maps and Maps-L subscribers,
The query subjoined was answered by a couple of MapHist subscribers this
week (including, rather weakly, myself). As I felt that more responses
would come from either, or both, of the Lists now being asked I am thus
forwarding the query (with Adrianne Wortzel's permission) to these two
Lists. I have taken the liberty of adding to the 'Subject' the
parenthetical "(paleo-geology)". Perhaps it should also be forwarded to a
geological List - if someone would kindly oblige?
Thankyou,
Francis Herbert (Curator of Maps, RGS-IBG)
[log in to unmask]
http://www.rgs.org
> -----Original Message-----
> From: Adrianne Wortzel [SMTP:[log in to unmask]]
> Sent: 12 November 2000 11:38
> To: [log in to unmask]
> Subject: Number of continents
>
> Dear Maphist:
>
> For a project, I would appreciate some help with questions concerning the
> number of continents ----
>
> Can anyone direct me towards finding out the correct number (and the names
> ) of continents during the several periods below to the present?
>
> Permian time of Pangaea, 225 million years ago = 1 (Pangaea)
> Triassic time of Laurasia and Gondwanaland, 200 million years ago = ?
> Jurassic time, 135 million years ago = ?
> Cretaeceous time, 65 million years ago = ?
> The Present = 7? - And Is this the count (7) for The Present? AFRICA,
> ANTARCTICA, ASIA, AUSTRALIA/OCEANIA, EUROPE, NORTH AMERICA, SOUTH AMERICA
>
> Thank you.
>
> Adrianne Wortzel
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|