Page 280 - Fundamentals of Geomorphology

GLACIAL AND GLACIOFLUVIAL LANDSCAPES 263

Table 10.3 Landforms created by glacial deposition
Orientation with Landform Description
ice flow
Supraglacial (still accumulating)
Parallel Lateral moraine A moraine, often with an ice core, formed along the side of a valley glacier
Medial moraine A moraine formed by the coalescence of two lateral moraines at a spur
between two valley glaciers
Transverse Shear or thrust moraine Ridges of debris from the base of a glacier brought to the surface by
longitudinal compression
Rockfall Rockslides from the valley-side slopes deposit lobes of angular debris across
a glacier
Non-orientated Dirt cone Cones of debris derived from pools in supraglacial streams
Erratic A large, isolated angular block of rock carried by a glacier and deposited
far from its source
Crevasse fill Debris washed into an originally clean crevasse by surface meltwater
streams

Supraglacial during deposition
Parallel Lateral moraine A moraine, often with an ice core, formed along the side of a valley glacier
(in part subglacial)
Moraine dump A blanket of debris near the glacier snout where several medial moraines
merge
Non-orientated Hummocky (or dead A seemingly random assemblage of hummocks, knobs, and ridges
ice/disintegration) (composed of till and ill-sorted clastic sediments) that contains kettles,
moraine depressions, and basins
Erratic A large rock fragment (clast) transported by ice action and of different
composition from the local rocks
Subglacial during deposition
Parallel Drumlin An elongated hill with an oval, egg-shaped, or cigar-shaped outline
Drumlinoid ridge Elongated, cigar-shaped ridges, and spindle forms. Formed under ice in
(drumlinized conditions unsuited to individual drumlin formation
ground moraine)
Fluted moraine (flute) Large furrows, up to about2min wavelength, resembling a ploughed field.
Found on fresh lodgement till (till laid in ground moraine under the ice)
surfaces and, occasionally, glaciofluvial sand and gravel
Crag-and-tail ridge A tail of glacial sediments in the lee of a rock obstruction
Transverse De Geer (washboard) A series of small, roughly parallel ridges of till lying across the direction of
moraine ice advance. Often associated with lakes or former lakes
Rogen (ribbed, A crescentic landform composed chiefly of till, orientated with its long axis
cross-valley) normal to ice flow and its horns pointing in the down-ice direction
moraine
Non-orientated Ground moraine: A blanket of mixed glacial sediments (primarily tills and other diamictons),
characteristically of low relief
Till plain Almost flat, slightly rolling, gently sloping plains comprising a thick blanket
of till
Continued