File:Lock 60 C and O Canal from NPS.jpg

English: Lock 60, 3rd Composite lock, on Chesapeake and Ohio Canal. NPS site says: Lock 60 is the third of the 13 composite locks. These locks differ from the other locks on the canal. Between the upper end of the lower gate pockets to the lower end of the upper gate pockets the stone walls were moved 9 and one-quarter inches on each side, resulting in a clear dimension between lock walls of 16 to 16 and one-half feet rather that the 15 feet previously adhered to. The normal clear dimension was resumed both up and down from these points. The walls were of rough-cut and rough-coursed limestone, principally dry-laid where the walls were widened and mortared in the other areas. The wider area was filled in with 5 one-quarter inch square timbers. This wooden section of the lock was “water-proofed” at first by being “kyanized” and later with creosote.

The wood timbers required frequent replacing, and around 1900 many repairs were made by stripping out the wood and pouring a cement liner, but at Lock 60 cement was not used. All of the wood coping and most of the wood lining at Lock 60 is gone, but a few remnants remain.

In the mid-1870s, Lock 60 was extended at its lower end by rock-filled wood cribbage, in order to double its length. The wooden portion of the extension is gone, but the lines of rock remain