Something strange in Stonehenge image?

[Sunny-side-up]

Was just watching this Vid
"Ancient Aliens - The Monoliths"

http://www.dailymotion.com/video/xz6j9i_ancient-aliens-the-monoliths_shortfilms#.UXVGXLXvvxY

and I noticed something maybe strange?
At position 06:54. If you look at the base of the stone to the right of picture you see what looks like it has a rectangular inner core of a different material?

http://i1188.photobucket.com/albums/z413/Alanshots/f8844385-d40a-4c77-a1d1-ea3a0a17cdc0.jpg (http://s1188.photobucket.com/user/Alanshots/media/f8844385-d40a-4c77-a1d1-ea3a0a17cdc0.jpg.html)

Almost like the outer skin of grey stone has fallen off revelling an un weathered core material.
Now is this some kind of recent repair work?


This might be totally explainable!
Anyone know?

[Richard S.]

Very good observation...

[Billy]

This is polished concrete, This is done in recent times to stabilize the crumbling or damaged footings of the stones.