GEOL 3000
Surficial Geological Maps
with a brief overview of glacial
processes and deposits
Surficial
Geologic
Maps
Show the
distribution of
unconsolidated
earth materials
and commonly
landforms at the
near surface
Soil Map
Soil maps classify units by soil fertility of
surficial material, which has been variably
affected by in situ chemical weathering
Surficial Geologic Map
Surficial geologic maps denote unconsolidated
material deposited at the site by some recent
geologic processes
Components of Surficial Geologic Maps
Map units - defined by the age, composition, and
environment of deposition
• Stream deposits –river alluvium, alluvial fans, floodplains
• Glacial deposits – recessional moraines, ground moraine till,
glaciofluvial (outwash) deposits, glacial lake beds
• Coastal deposits – tidal areas, deltas, lagoons, reefs, beaches
• Slope deposits – talus, mudflows, landslides, colluvium
• Wind-laid deposits – sand dune field, loess, volcanic ash
• Spring deposits – tufa, geyserite
• Lake deposits – playa lake beds, peat beds
Landforms - denoted by linework that outlines, traces, or
shows the orientation of topographic features related to
geomorphic landforms (e.g. stream terraces, sand dunes,
spits, alluvial fans, sand dunes, scarps, drumlins, eskers,
moraines, glacial straitions)
Environments of Surficial Deposits
Shapes of surficial deposits tend to generally have coplanar upper and
lower contacts, but on a larger scale, tend to be non-sheet-like
Continental Glacial Deposits
Glacial Map Unit and Landforms
Pine County MN
Shapes of Surficial Geologic Units
Washington County
Pine County
Map Patterns on Quaternary Geologic Maps
The Pleistocene Epoch
THE ICE AGE
~2,000,000,000-10,000 years
Zone of Accumulation
Zone of Ablation
Myrdasjokull Ice Cap, S. Iceland, 1999, C.Jennings
Glaciers:
Nature’s
Bulldozer
Advance
Erosion
Retreat
Deposition
Powerful Agents of Erosion
glacial striations
Dirty
Ice
Deposits from Ice
Till
Deposits from
Meltwater
Outwash
Common Continental Glacial Landforms
formed during glacial retreat
Recessional
Moraines
Driftless
Area
Glacial Outwash
Plains
Iceland
Alaska
Pro-glacial
Lakes
Lake
Winnebago
The Last Glacial Retreat out of Lake Superior
Glacial Lake
Agazzi
The Mother of
All Pro-glacial
Lakes
Bemis Moraine
The Dam
Glacial River Warren/
Minnesota River
The Spillway
Lake-riddled
Ground
Moraine
Formation
of Kettle
Lakes
ESKERS
subglacial
river
deposits
DRUMLINS
Stream-lined
Hills
Toimi Drumlins
St.Louis/Lake Cos.
Minnesota’s
Landscape:
The Legacy
of the
Glaciers
Glacial Deposits of Minnesota
The Invasion of the Canadian Ice Lobes