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Using topo maps to guess historical land use

1935 map

My post about walking distance got me thinking about changes in our area over time.  I wanted to go back and look at some old USGS maps, and was surprised to learn that you can now download all of the maps from your region as pdf files for free!  (The last time I played with topo maps, about six years ago, you either had to buy a paper copy from the USGS or snag screenshots from various websites that were trying to sell paper maps.)

For our area, the maps available were from 1935 (first map) and 1957 (second map), and I also took a screenshot of google maps' current satellite photo (third map) for a more up-to-date view.  Then I layered them all together in the Gimp.  I cropped a bit of the 1935 map off and made the top map slightly transparent in the first image in this post so you can see what I'm talking about when I refer to layering.

1957 map

The property I'm taking a look at here is the same potential Walden Effect annex I mapped the soil for.  I was interested to see that, except for the ridge (south end of map), the propery was entirely devoid of trees between 1935 and 1957.

Solid black squares on a topo map represent houses, dotted lines are small roads or trails, and outlined squares are generally barns or other large, non-residential structures.  With that information in mind, you can see that someone was living on the property during both 1935 and 1957, probably grazing animals or possibly growing corn and tobacco on most of the acreage.

Current map

Between 1957 and the present, the majority of folks stopped farming in our region and started getting jobs in town.  Although it's sad that people were no longer living off the land, the earth rejoiced by sprouting up trees everywhere.  Only a few acres on the northwest side of the property remained clear of trees by the time of the 2011 aerial photo.

Tree canopy over time

I merged all three of these maps together to create the version above, which gives a rough estimate of canopy cover over time.  The lightest color is areas that are currently forested, the bright green represents 1957 trees, and the dark green is 1935 trees.  (I didn't bother with the area on the other side of the river, and you'll notice some irregularities between 1935 and 1957 forest borders that are probably a sampling error due to the low resolution on the earlier map.)

Why does it matter which areas had trees in the past?  It's handy to know that the woodland is at least 77 years old on the ridgetop, because that kind of forest will be chock full of plants and animals found in few other places and is best left alone.  On the other hand, twenty-plus years of farming on the rest of the property may mean the topsoil has been eroded away, and definitely means I'll feel less guilty about clearing spots for sustainable agricultural purposes.  And, of course, it's just plain fun to guess what the land was like decades in the past.

Have you discovered even better sources of historical maps or aerial photos online?  Since it's the weekend, I can probably sink my teeth into some more....

Our chicken waterer keeps the flock healthy when I get sidetracked into map-land all day.


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I haven't been able to get the link yet, but hope to later--This is a good start, and bears careful study. Thanks--mom
Comment by adrianne Sat Aug 18 07:45:57 2012
In the sixties we used to visit the property in Arkansas where my Grandfather grew up. As he grew up the family kept 600 acres or more planted in cotton and whatever crops they used on the farm. When they moved to the property about the turn of the last century, they had clear-cut the land and then stopped farming sometime in the 20's. When we visited in the 60's all that could be found of the house and outbuildings were ruins surrounded by huge trees. The trees were all large enough to be sold as timber, so it doesn't take too long for nature to take over once we step away from the land.
Comment by Patti Smith Sat Aug 18 21:32:29 2012

Mom --- I hope you figured out the link!

Patti --- It's true that trees come back pretty quickly, but it does take decades to regain real forest characteristics. I figure if a forest is at least thirty or forty years old, we should preserve it's momentum, and let it keep going if at all possible....

Comment by anna Sun Aug 19 19:15:43 2012

http://www.historicaerials.com/

This site may be of some help. In some areas they have a lot of the aerial photos dating back to the 50's, but other areas just include the older Topo maps.

Comment by Brian Mon Aug 20 15:38:45 2012
Brian --- I took a look at that site when I was wandering around looking for aerial photos. Maybe it's just for our area, but they seemed to have the same selection of maps that the USGS had...but marked up with ugly watermarks unless you paid for extra access.
Comment by anna Mon Aug 20 16:43:42 2012
I am amazed that the google image (which is dated 2012) of your place doesn't show more evidence of your existence. It's as if "the aliens" couldn't even see you. I would have thought the trailer and the gardens sould be easy to spot.
Comment by Anonymous Wed Oct 10 15:14:37 2012
Anonymous --- This isn't our homestead, just a tract of land we were looking at. You can see a recent aerial photo of our core homestead here.
Comment by anna Wed Oct 10 15:31:15 2012

One very unique homestead, $1,500 per acre, the opportunity of a lifetime