Google Earth is a no-brainer for geography and history teachers but it’s also a handy-dandy tool for teachers of all grades and content.

But one of its strengths can also be a weakness.

There’s just so much stuff.

With hundreds of layers with thousands of maps, images, 3D buildings, live traffic data, news, earthquakes and a partridge in a pear tree, it can sometimes get a bit overwhelming.

I’m starting to discover that many teachers are getting lost in there. And people are missing some pretty cool stuff. One of the coolest that you may not be aware of is the Rumsey Historical Map layer.  These maps live in the Gallery section in the Layers area of Google Earth.

The Rumsey layer is just a small sampling of over 150,000 maps that David Rumsey has collected over the years. On his site, he’s posted more than 20,000 of his maps. And Google Earth has around 120 of those on six continents from different time periods.

All the maps contain rich information about the past and represent a sampling of time periods (1680 to 1930), scales, and cartographic art, resulting in visual history stories that only old maps can tell. Each map has been georeferenced, thus creating unique digital map images that allow the old maps to appear in their correct places on the modern globe.

Some of the maps fit perfectly in their modern spaces, while others (generally earlier period maps) reveal interesting geographical misconceptions of their time and therefore have to be more distorted to fit properly in Google Maps and Earth. Cultural features on the maps can be compared to the modern satellite views using the slider bars to adjust transparency.

When you turn the Rumsey layer on, compass rose icons will appear around the world. Clicking on an icon will open a window with specific information about that map. Clicking directly on the map thumbnail will load the map overlay.

Each map window in Google Earth also has a link back to David’s site with more information about that particular map. Another incredibly cool thing about the images is that David has posted them under a Attribution-Noncommercial-Share Alike Creative Commons license. This basically allows teachers to “to copy, distribute and transmit the work” as long as they cite the Rumsey source and use the image for non-commercial purposes.

Other fun and useful layers exist deep in GE. Ya just gotta take some time to dig ’em out.

You might also subscribe to Google’s Long/Lat Google Earth blog, an independent Google Earth blog and maybe even Google Maps Mania. Both give helpful updates and links to Google Earth resources.

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