2 results containing "Salt mining."
[Saltpeter cave, Natural Bridge, Va.]
[between 1900 and 1915] | 1 negative | Detroit Publishing Co.
LC-D4-500570 <P&P> [P&P] | LC-DIG-det-4a25526 (digital file from original)
[Interior of salt mine]
[between 1915 and 1925] | 1 negative | Detroit Publishing Co.
LC-D420-2347 <P&P> [P&P] | LC-DIG-det-4a27857 (digital file from original)