ICE FLOW MAPPING
In addition to mapping sediment and landforms deposited by glaciers, determining how
glaciers moved over time is fundamental for drift prospecting and mineral exploration, as it
provides the foundations for interpretation and modeling glacial dispersal.
Ice Flow Features
Determining Relative Ages
Ice-movement indicators
include both small-scale
features (mainly erosional) on
bedrock and large scale
features (depositional). Smallscale erosional features
include non-directional
indicators such as striations,
grooves, and chattermarks,
and directional indicators such
as nail head striations,
lunate/crescentic fractures
crescentic gouges and rôches
mountonnées.
The relative ages of the erosional
ice-flow indicators are commonly
determined from cross-cutting
relationships (right) and lee-side
preservation.
Glacial striations indicating that glacial ice
movement was parallel to the pencil.
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Ice Flo
For depositional features, multiple
ice flow directions may be
preserved. Usually the features
deposited by the earlier ice flow
are removed by the later event;
however the superposition of
younger features on streamlined
landforms may also be preserved.
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Lak
Ind
Medium-scale erosional features, such as this rôche
mountonnée, provide information on ice flow
direction.
Ice
Cross-cutting striations indicate two glacial
ice movements where an older ice-flow (red
arrow) is cross-cut by a younger ice-flow
(yellow arrow).
Regional Patterns
ian
Glacial depositional landforms,
either oriented parallel to ice
flow (flutes, drumlins, cragand-tail hills) or perpendicular
to ice flow (various types of
moraines) provide evidence of
paleo ice flow.
Striation
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Re
Flo
w
w
Ice Flo
Lake
ria
to
Vic
Large scale features are identified from
aerial photographs and include flutes
(shown above), crag-and-tail hills and
drumlinoid landforms.
Moraines form along the terminus of the glacier or
under the ice, leaving ridges of till that are
perpendicular to ice flow.
Based on numerous ice
flow indicators, a
regional pattern of ice
flow can be established.
In the Red Indian Lake
basin (left), an early
southward ice flow
across the region was
followed by a westward
ice flow in the eastern
part of the basin and a
northeastward ice flow
in the western part. On
this basis, an ice divide
(dashed line) can be
inferred to have existed
during the later stages
of glaciation in the area.