,
Northwest Territories, Canada; notice the contiguous, wavy rows of glaciated bedrock which resemble old-fashioned wigs as mentioned by Horace de Sassure The contrasting appearance of the erosional stoss and lee aspects is very defined on roches moutonnées; all the sides and edges have been smoothed and eroded in the direction travelled by the glacier that once passed over it. It is often marked with
glacial striations. The rough and craggy down-ice (leeward) side is formed by
plucking or quarrying, an erosional process initiated when ice melts slightly by pressure and seeps into cracks in the rock. When the water refreezes, the rock becomes attached to the glacier. But as the glacier continues its forward progress it subjects the stone to
frost shattering, ripping chunks away from the rock formation. Studies show that the plucking of the lee side is a much more significant erosional process than the abrasion of the stoss side. The side profile of a stoss and lee glaciated, bedrock knob (an erosional feature) is opposite to that of a
drumlin (a depositional feature). In a drumlin, the steep side is
facing the approaching glacier, rather than
trailing it. Even larger examples are known from Sweden where they are referred to as
flyggbergs. Ice-smoothed bedrock bumps which lack the steep, plucked lee side faces are referred to as
whalebacks or
rock drumlins. Roches moutonnées may not be entirely glacial landforms, since they may have already had a similar shape
before glaciation.
Jointing that contributes to their shape typically predates glaciation, and roche moutonnée-like forms can be found in tropical areas such as
East Africa and
Australia. Further, at
Ivö Klack in Sweden, rock surfaces that have been exposed by
kaolin mining and then become weathered resemble roches moutonnées. ==See also==