Report on the building and ornamental stones of Canada (1912)
Parks, William A. (William Arthur), 1868-1936, Canada. Mines Branch (1901-1936) · Ottawa : Dept. of Mines, Mines Branch · leaf 158
mmmm- Vie. 6. Method of opening a (luariv in the form of truncated pyramids connected bv tuniici. At the base of this opening, on the two sides facing the strike of the l)eds,tunnels are driven through the poorer upper material, by the careful use ofmild oxi)losives. These tunnels may extend along…
Building stones · Geology, Economic · Stone industry and trade
Internet Archive · University of Toronto, Robarts Library · Public Domain Mark 1.0. Free to use for anything.
