Heppner, Oregon and its roller-compacted concrete backstop

The cross-hair in the Flash Earth image below is just behind home plate at the city's baseball field. Note the backstop...the Willow Creek Dam. Sure, it is pretty much the backdrop for the whole town, but the proximity to the ball field is just...so...close.

Further reading...worth a look, for sure:

http://www.wrh.noaa.gov/pqr/paststorms/index.php

http://www.nww.usace.army.mil/dpn/images/willow305.htm

http://en.wikipedia.org/wiki/Roller-compacted_concrete

Hmmm...interesting. Think you should go check it out: Flash Earth link