Hi,
In trying to find the gauge of the B&O (4'8", 4'8 1/2" ...), I found an unknown (to me) Confederate raid on the B&O during 1861 that took control of the B&O for about 30 days.
"Great Train Raid of 1861" - the confederates took 8 locos and 60 pieces of rolling stock from the B&O and put them on the Confederate RR system.
This (to me) sounds as great as the Great Locomotive Chase of 1862. Apparently the B&O equipment was broad gauged to 5'.
Just interesting history.
Back to the granite blocks for the B&O, it seems to me I heard of a construction site in Ohio (?) where they found granite blocks and rust marks in the ground. It was about 6-10 years ago if I recall correctly and I do not recall enough to try to find any hits on the internet about it.
Oh well.
Doug vV