Posted by Chris M Monday, February 2, 2009

Google Earth Historical Imagery

A couple week ago, BrianR at Clastic Detritus showed off the new higher-resolution bathymetry coverage in google earth. Well, version 5.0 was released today and it has some other fun stuff to play with. I like the historic imagery.

The pain about historic imagery is finding it and getting in a usable format on your computer. Even if you not going from a paper image, it still requires some work. Well google has gathered up some old imagery. Older than 20 years is pretty spotty, but there are some locations worth checking out.

The below images are of southern Lake Tahoe from 1940, 1969, 1987, 2004, and 2007. The resolutions are low, so I suggest opening the location up in google earth (38°56'14.56"N, 120° 0'38.81"W, 4.4 km altitude).

In 1940, notice the large marshland in the middle and the elongated delta of a stream in the NE.

Now in 1969, the marshland is a marina and the delta is reduced in size on the NW (sediment no longer allowed to replace erosion of delta?). Even the stream feeding the delta has been channelized.

In 1987, a spit has developed on the NE side of the stream's mouth.

It is 2004 and there is a new delta. Why is it forming now? Perhaps there is an increased sediment supply from the stream or dredging is no longer occurring?

Finally, we are at the newest image in 2007. The delta is gone again!


ScienceWoman said...

That's really cool stuff. I'm definitely going to have to check it out.

Dr. Jerque said...

Also check out the delta of the Walker River below Schurz, NV for evidence of some dramatic and dynamic fluvial effects of upstream water diversion.

Chris M said...

Dr. Jerque, you are not kidding. amazing!