The Snowplough turn (also known as the wedge turn or stem turn) is a development of the stem technique, where the uphill ski is stemmed or pushing out from being parallel with the downhill ski to form a V shape.
Both techniques described below were included in Mathias Zdarsky's book Lillienfeld Skilaufer Technik in 1896.
Snowplough / Wedge
The Snowplough or Wedge involves forming a V shape with the skis. By applying pressure against the snow with the edges of the skis - taking care not to cross the tips of the skis - speed can be controlled or brought to a stop.