Clay Pipes
Tobacco came from the New World to Europe ca. 1528 and clay pipes were developed along with this new import. During the 18th century, political rifts between the U.S. and Europe reduced British access to tobacco, and snuff, made of smaller amounts of crushed tobacco, became the popular form of tobacco used. The clay pipe was not used so frequently during that time, but they made a resurgence in the 19th century. I'm not sure if the statistics are the same in North America where tobacco was grown - but British clay pipes were undoubtedly harder to acquire at that time.
Clay Pipes are most often white, being made of Kaolin (the clay used to make porcelain). They will often have staining from the ash and smoke. I have found pipe stems in my garden from the 1920s or 1930s - often in this late period, they were used by children for blowing bubbles. Pipe stems could indicate a pre-1846 site, or any time before or up to 100 years later. They went out of fashion with the popularity of the cigarette.
The clay pipe evidence you are most likely to find in British Columbia are pipe stem fragments. Normally about 2-5 cm long, they are just white cylinders of clay with an often off-centre hole and mould seams running down either side (maybe). Some pipe stems were also decorated, and many had the name of the maker embossed on the side.
This is a 2.5 cm long pipe stem fragment I found in my garden a couple of years ago. It is porous, which means it was made by pouring liquid clay into a mould. Pipes were also made of solid clay that made them heavier. There were 2 main methods of making them, much like a poured ceramic figure vs. a thrown or moulded plate or cup. The pipe stems were long (very long on some) and they would regularly break off. The pipe would be used until the stem was too short to cool the smoke.
Image from the UBC Museum of Anthropology showing a less porous type. Found at a Coast Salish site.
Image of pipes and pipe-making tools from the 18th century. Wellcome Collection 42865i