Headstones at Arlington dumped in stream to stop erorsion?

Did they think of just using ROCKS instead of headstones?

Arlington headstones in stream to stop erosion

The Associated Press
Posted : Wednesday Jun 23, 2010 18:05:09 EDT

ARLINGTON, Va. — Army officials say that old headstones found lying in a stream on the grounds of Arlington National Cemetery had been placed there deliberately for erosion control.

The tombstones were found by reporters for The Washington Post earlier this month in the aftermath of an internal Army investigation that found chaotic management at the cemetery and the apparent mislabeling of more than 200 graves. Cemetery officials at first could not say why the tombstones were in the stream.
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http://www.armytimes.com/news/2010/06/ap_grave_stream_062310/