Saw the ones at the arboretum, but never knew bits were dumped within Rock Creek Park. Rode near them on my bike many times.
A similar thing happened to NY’s Penn Station. When McKim, Mead & White’s masterpiece was demolished in 1963 to make room for the current Madison Square Garden, most of the beautiful pink granite statuary was unceremoniously dumped in the NJ meadowlands.
Penn Station was not yet 50 years old at the time of its demolition.