Lyman Viaduct II

When seeing the Lyman Viaduct today as shown here, it is hard to imagine exactly what is buried beneath the sand and gravel.

Colchester, CT

One can look down the side of the viaduct and see Dickenson Creek 137 feet below, which still flows through the viaduct thanks to some culverts that were installed when the original trestle was buried.  

I was impressed with the size of the "gravel" rocks seen here.  Most of the gravel is at least as big as one's fist if not bigger.  I wonder how they were able to dump so much sand and gravel here and pile it up 137 feet for a distance of over 1100 feet.  I don't think there are any roads nearby or other ways to access this area.  I wonder if trains were used to dump the gravel?  However, if one looks carefully, you can find some hints of what lies buried beneath, like this rusty bolt sticking out of the ground....

Or the rail running in front of this bench.