-------- Original Message --------
Subject: RE: Re: Ancient topography of a specific place
Date: Tue, 29 Nov 2011 11:29:27 -0500
From: Cloutier, Barb <[log in to unmask]>
To: Maps, Air Photo, GIS Forum - Map Librarianship <[log in to unmask]>
Elizabeth,
Maps of post-glacial isostatic rebound rates may give a sense of how
things have been changing over the last 15 000 - often shown in relation
to neotectonic effects (earthquake activity due to rebound effects in
crust). Also, maps that show shoreline/marine limit changes related to
post-glacial isostatic rebound of the Earth's crust or related to
sea-level changes during the glacial and post-glacial periods.
Here is an example of rebound rates and marine limits from the Atlas of
Canada web site -
http://atlas.nrcan.gc.ca/site/english/maps/archives/4thedition/environment/land/035_36
or this PowerPoint presentation on use of GPS in tracking rebound -
www.earth.northwestern.edu/people/seth/Texts/Pressconference.ppt
There are also "drift thickness" and "overburden thickness" maps that
show depth of surficial (unconsolidated) materials. If the age of these
materials is known, you can see how much the topography would change if
they were removed - especially channel-fill and valley-fill deposits.
Here is an example from the Ottawa area -
http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.fl&id=fastlink&pass=&format=FLSHORTORG&search=R=132040
The Ontario Geological Survey did a number of these for southern Ontario
which reaches down to 42 degrees North.
http://www.geologyontario.mndm.gov.on.ca/
Hope this helps.
Barb
Barb Cloutier
Subject Specialist Spécialiste en la matière
Natural Resources Canada Library Bibliothèque de Ressources naturelles
(Earth Sciences) Canada (Sciences de la Terre)
Natural Resources Canada Ressources naturelles Canada
Government of Canada Gouvernement du Canada
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Ottawa, Ontario K1A 0E9 CANADA Ottawa (Ontario) K1A 0E9 CANADA
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943-1549
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sciences
de la Terre
-----Original Message-----
From: Maps, Air Photo, GIS Forum - Map Librarianship
[mailto:[log in to unmask]] On Behalf Of Angie Cope, American
Geographical Society Library, UW Milwaukee
Sent: November 29, 2011 10:01 AM
To: [log in to unmask]
Subject: Re: Ancient topography of a specific place
-------- Original Message --------
Subject: RE: Ancient topography of a specific place
Date: Tue, 29 Nov 2011 09:59:24 -0500
From: Grabach, Kenneth A. Mr. <[log in to unmask]>
To: Maps, Air Photo, GIS Forum - Map Librarianship <[log in to unmask]>
The range of years is a pretty big difference, and the latitude crosses
a lot of terrain. So these are some pretty general ideas.
For a thousand years ago: topographically speaking, the landscape would
look about like it does now, river courses about the same, mountain
areas and plains about as they are now. The biggest change would be
that introduced vegetation would not be there. So a map of natural
vegetation, especially 'potential natural' vegetation would be a good
guess of what was where. There are two maps, both by A.W. Küchler, that
are well known. The easiest to come by is the one in the National Atlas
of the United States, sheet 90.
Another larger in scale, is Potential Natural Vegetation of the
Conterminous United States, published by American Geographical Society,
1964. This has an accompanying text, with a photograph of each of the
vegetation types. While they focus on the plant cover for that zone
type, they do give a sense of some topography where each type occurs.
I recommend both these maps.
For a million years ago: this was in the middle of the glacial periods
(am not sure whether it would be Illinoisian or Wisconsinian or
interglacial period). There are maps of surficial geology, and
Quaternian period, that would help with this. Here I don't have
specific maps to recommend, but this is the approach I would use to
begin with for this period.
One of the things to keep in mind here is that present-day river courses
are different in the glaciated regions than before or during the glacial
periods. For example, there was not a river that we would recognize as
the Ohio River. The one we call New River and Kanawha River would seem
to have a northern extension, the Teays.
Books on glacial history of North America will give good text and
probably some illustrations that would help to estimate this.
Ken
Ken Grabach <[log in to unmask]>
Maps Librarian Phone: 513-529-1726
Miami University Libraries
Oxford, Ohio 45056 USA
-----Original Message-----
From: Maps, Air Photo, GIS Forum - Map Librarianship
[mailto:[log in to unmask]] On Behalf Of Angie Cope, American
Geographical Society Library, UW Milwaukee
Sent: Tuesday, November 29, 2011 9:31 AM
To: [log in to unmask]
Subject: Ancient topography of a specific place
-------- Original Message --------
Subject: Ancient topography of a specific place
Date: Tue, 29 Nov 2011 09:16:22 -0500
From: Elizabeth Psyck <[log in to unmask]>
To: [log in to unmask]
Good Morning,
I have a particularly challenging question today - I've been asked if
there is "something where I could find out about the topography of an
area from 1000 years ago or a million years ago". We don't need anything
extremely detailed, just a general idea. The specific area we're looking
for is the area around 42nd parallel in North America, but if you can
suggest anything, we can probably make it work.
Thanks everyone,
Elizabeth
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