Topo the world!

I don't know why it took me so long to realize this, but after learning how to use google earth image overlay thanks to an instructional video on Youtube (where else?!), and using a hand-drawn, not-to-scale trail map as my first project (the Ghost of Coldspring Valley), it occurred to me that the problems of scale were easily solved by using a topographic map image that was to scale! I laid the topo image over google earth's satellite of the area, matching perfectly the roads and railway bed on the perimeter of the valley, and presto:
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I chose this level of opacity, so you can see the topo features of Ancaster Creek and the roads, and beneath (or through) that, the current google earth satellite of the area.

We can see how far McMaster pushed the creek out of the way to make more space for parking, and the round blue line near the centre of the image below the western end of Sanders Blvd representing the location of Binkley's Pond.

The pink line is a GPS track I made showing the path of Maria's Walk, the only surviving trail (broken only by the parking driveway road) from the Coldspring Valley Nature Sanctuary of the Royal Botanical Gardens (1958-1963).

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This screen shot is with a slighter different opacity, that reveals the google earth satellite in a bit more detail (doesn't show the GPS track for Maria's Walk)

You have no idea how thrilled I am to have figured this out!