Continental Environments

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Continental Environments
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Fluvial Systems Alluvial Fans

• Fluvial Deposition
• next to young uplands
• often along fault trends
• Cone-shaped, poorly sorted and
• gravel-rich sediments deposited
• along steep slopes
• Three different sorts of Fans

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Alluvial Fans Debris-Flow-Dominated Fans
Mid-Fan -Debris Flows And Sheet Flows
Inner Fan - Channelized Debris Flows
1s to 10 km Steep Slope Arid,
flashy Environments
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Alluvial Fans Braided Alluvial Fans
Inner Fan - Longitudinal Gravel Bars
Mid-Fan - Longitudinal Gravel Bars and
Transverse Bars
Outer Fan - Transverse Bars and Dunes
10s of km Slope less than 1
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Fluvial Systems Alluvial Fans

• Well-Vegetated and
• swampy environments
• Meandering streams
• across a low slope
• Well-sorted, muddy
• sediments
• Difficult to recognize
• in ancient deposits

10s of km Low Slope 0.02 Humid Climate
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Alluvial Fans
Modern- Significant deposits in Arid, Mountainous
Terrain Ancient - Important during Pre-Cambrian
and early Paleozoic, Permian-Triassic time
periods Alluvial Fan Deposits are Commonly
associated with Playa, Lake, floodplain and
eolian dune deposits.
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Fluvial Systems Braided Rivers
Distinguishing Characteristics Low sinuousity,
numerous channels separated by islands and
bars High Sediment load, high energy gravel and
sand-dominated systems
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Fluvial Systems Braided Rivers Structures
Lateral and Transverse Gravel and Sand Bars
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Transverse And Linguoid Dunes
Longitudinal Dunes
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Fluvial Systems Braided Rivers Bedforms
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Fluvial Systems Braided Rivers Bedforms
Trough-Cross Stratification
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Fluvial Systems Braided Rivers Modern Mountain
Streams, Glacial Outwash Plains. High-gradient,
coarse- Sediment-choked flood Plains Ancient Not
well represented, But some good examples From
nearly every time- period
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Permian, New Mexico
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Why does all this matter?
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Section 1
Section 2
Section 3
Los Colorados Fm
Cuerva de Sal
Valle de la Luña
Ischigualasto Formation
Ischigualasto Formation
Cancha de Bochas
La Peña
OLDER TRIASSIC
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Paleoflow Orientations
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Fluvial Systems Meandering Rivers

• Confined to single, major
• sinuous channel.
• Sediment Transport that
• includes lateral transport
• Low gradient, fairly low
• energy streams.
• Typically discharge into
• DELTAS in Lakes and Seas

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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers Levee Deposits
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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers OXBOW PONDS
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Fluvial Systems Meandering Rivers OXBOW PONDS
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Fluvial Systems Meandering Rivers
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Fluvial Systems Meandering Rivers Vertical,
upward fining sedimentary deposits.
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Fluvial Systems Meandering Rivers
Well Represented through the Stratigraphic Record,
especially after Devonian Time
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Eolian Desert Systems
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Eolian Desert Systems Transport Processes
3 Principle Methods
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Transport Processes
Suspension -Smaller dust size particles removed
by deflation may be transported great distances
as they are carried high in the
atmosphere. Saltation -Particles too heavy to
be continuously carried aloft bounce or skip
along the surface as they are periodically
lifted. -This process accounts for approximately
80 of eolian transport and is responsible for
most of the abrasive erosion of rock
material. Creep -Saltation of medium size
material results in the collision of these
airborne particles with larger material at the
surface these collisions can dislodge and move
much larger material.
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Suspension
North Africa
Africa Atlantic Coast
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Desert Pavement
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Saltation
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Eolian Depositional Landforms -Ripples are not
actually depositional landforms but form as
saltating particles are transported resulting
in consecutive crests and troughs oriented
perpendicular to the prevailing wind
direction. -The most common depositional
landform is a dune which forms as wind flows
around/over and object. -Dunes may be defined as
either free dunes, which migrate in the direction
of the prevailing or strongest winds, or tied
dunes which are stationary, attached or
stabilized by vegetation or topography. -Dunes
all have a windward and leeward side (slipface)
the windward side is typically a gentler and
the leeward side is the steeper slope ( equal to
angle of repose). -Dunes migrate as material
constantly moves up the windward side and is
deposited on the leeward side.
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Eolian Desert Systems Dunes-Morpology
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Eolian Systems 5 major types of Dune Morpologies
Main Dune Types 1 - Parabolic Dune 2 - Barchan
Dune 3 - Star Dune 4 - Seif or Longtitudinal
Dune 5 - Transverse Dune
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Eolian Desert Systems Dunes-Morphology
3 Primary Controls Sand Supply Wind
Energy Vegetation (water)
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Eolian Dunes-Morpology Barchan Dunes Tranverse
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Barchan Dunes
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Eolian Desert Systems Transverse Dunes
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Transverse Dunes
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Parabolic Dunes
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Parabolic Dunes
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Longitudinal Dunes
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Star Dunes Winds from several directions
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Cross Bedding - - Probably most common
Three Types (1) Planar (Tabular) (2) Trough (3)
Tangential
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Anatomy of Cross Bedding
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Planar (Tabular) Cross Bedding Transverse Dune
Ripple Migration
Relatively Common in Eolian
Envionrments
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Tangential and Trough Cross Bedding Unidirectional
Flow
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Trough Cross Bedding Lunate or Crescentic Dune
and Ripple Mirgration
Abundant in Eolian and Fluvial
Envionrments
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Modern Dune Field (erg) Large, Mobile
Dunes Large-scale X-bedding
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Modern Dune Field (Draa)
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Large-scale X-bedding Permian, AZ
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Inter Dunes Sand Sheets in Dry environments
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Inter Dunes Sand Sheets and Mudcracks
in Seasonally Dry environments
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Eolian Interdunes Systems Humid environments
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Burrows - Common in Interdunes In
humid Environments
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Bioturbation (footprints) -in Cross Section
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Eolian Desert Systems Sheet Sands
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Association of eolian sys- tems with other
deposi- tional systems
Pluvial Lake (Lacustrine)
Fluvial
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Association of eolian systems with other
depositional systems
Lake Shore, Michigan
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Association of eolian sys- tems with other
deposi- tional systems
Lacustrine
Fluvial
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Coastal
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Ancient Desert Deposits Vertical Successions
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Lacustrine (lake) Systems
1 of modern continental land surface. More
prevalent today than for most times in Earths
Past, Because continents are emergent--more land
area. Volumetrically small part of stratigraphic
record (lt1).
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Volcanic lake Systems
Crater Lake, Orgeon
9 kilometers (5.6 miles) across. Reds and yellows
shallower depths, greens and blues show the
deeper areas.
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Caldera Lake - Crater Lake, Oregon
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Caldera Lake - Crater Lake, Oregon
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Glacial Lakes
Kettle Lakes, Iowa
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Tectonic lake Systems
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Two basic sorts of hydrological systems
Open Lake - Rivers going into and out of
Lake Closed Lake - Rivers into, but not out of
Lake
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Lacustrine (lake) Systems Climate
Precipitation vs. Evaporation Lake Levels Amount
of Runoff Siliciclastic vs. Chemical input to
sediments Wind and Wind Strength
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Lacustrine (lake) Systems Physical Processes
Gravity and Tides are relatively Unimportant Wind
Climate and River inflow are important
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Lake Deltas
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Lake Deltas
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Gilbert-type Deltas
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Gilbert-type Deltas
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(lake) Systems Physical Processes
Wind Driven Waves Rework Sediment
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Sand Spits, strands and beaches
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Lacustrine (lake) Systems Seiches
Improves circulation and mixing of lake water
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Varves Characteristic Lake Deposits
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Varves Characteristic Lake Deposits
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Even Turbidites
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Open Lakes-dominated by clastics and O.M.
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Open Lake Modern
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Closed lakes
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Ephemeral Lake Systems
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Lacustrine (lake) Systems Chemical Processes
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Lake Systems Chemical Processes
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Lacustrine (lake) Systems Facies Associations
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Ancient Lake Deposits
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Lacustrine (lake) Systems Organic Processes and
Energy Resource
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Oil Shale
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Glacial Systems - limited to areas of permanent
snow and ice accumulation
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Glacial Systems - include elements of other
depositional systems, e.g. lacustrine, fluvial
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Glaciers cover 10 of modern Earth Antarctica
and Greenland
Glaciers cover 30 of modern Earth during last
glacial maximum, 21,000 ybp
Last Glacial Maximum
Holds 80 of fresh H2O
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Earths Icehouse-Greenhouse History
Global Temperature?
Late PreCambrian Icehouse
Greenhouse
Greenhouse
Greenhouse
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3 Basic kinds of glacial Systems
1. Valley Glaciers - relatively small
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3 Basic kinds of glacial Systems
2. Piedmont Glaciers - moderate size
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3 Basic kinds of glacial Systems
3. Ice Sheets - Continent-size glaciers
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What Makes Glaciers waxing, waning, equilibrium
Gravity Flow lines
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Glacial Systems Environmental Setting

• Basal/Subglacial zone
• Englacial
• Supraglacial
• Ice-contact
• Proglacial
• periglacial

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• Basal/Subglacial zone

Influenced by contact with underlying bedrock

• Ice is viscous
• plucks material from underlying beds
• Generates additional friction and sediment

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Glacial Striations
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2. Englacial - Interior of Glacier

• Plucked material is entrained within the ice
  body and transported to supra ice-contact zones.

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3-4. Supraglacial and Ice contact zones

• Zones of melting or ablation
• Accumulation of englacial debris from advancing
  portions of the melting glacier

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5A. Proglacial - Glaciofluvial environments
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5. Proglacial A. Glaciofluvial environments

• Sediment-Choked streams from englacial debris
  result in development of braided streams

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5B. Proglacial - Glaciolacustrine
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5B. Proglacial - Glaciolacustrine

• Finer sediments transported to lake depths

• Deltas develop at interface between fluvial and
  lacustrine environments

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5B. Proglacial - Glacioeolian
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6. periglacial

• Transport and deposition of silt-size materials
  from glaciers to more distant areas

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Transport and Depositon in Glacial Systems
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Glacier Proper Most sediment carried along bottom
and sides of glacier

• Sediments consist of EXTREMELY heterogeneous
  material from clay to boulder size.

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If Glacier is at equilibrium
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If Glacier is receding (waning)
Ground Moraine
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Resulting sediment is called a diamict, or till
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Glacial Till
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Some material is reworked by meltwater interior
to the glacier

• This results in some sorting, similar to stream
  processes

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Drumlins
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Drumlins
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Drumlin
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Eskers
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Eskers
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Eskers
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Proglacial and Periglacial deposits Most sediment
reworked by water or wind

• Sediments consist of generally well sorted
  material from clay to boulder size.

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Glaciofluvial deposits

• Braid-stream type deposits
• Longitudinal bars
• Transverse bars
• Lateral bars
• Trough x-bedding

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Glaciolacustrine deposits Deltas
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Gilbert-type Delta deposits
Coarse grained, steep foresets, shallow bottom
sets
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Prodelta glaciolacustrine deposits
Varved sediments are characteristic of glacial
lakes
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Ice-rafted debris
Drop Stones
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Ice-rafted debris
Ancient Drop Stones in Belize
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Glacial Systems Transport and Deposition
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Glacier
Rock Flour
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Abrasion of Lower Bedding Plane
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Forms Rock Flour
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Glacial Till
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Glacial Till
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Glacial Till
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Glacial Erratics
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Eskers
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Eskers
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Eskers
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Kames
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Kames
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Kames
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Kames
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Kames
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Drumlins
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Drumlins
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Drumlins
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Moraines
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End Moraine
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Lateral and Medial Moraine
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Medial Moraine
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Kettle Lakes
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Kettle Lakes
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Kettle Lakes
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Drop Stones
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Ancient Drop Stones in Belize
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Glacial Systems Transport and Deposition
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Glacial Systems Glacial Facies
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Glacial Systems Continental Ice Facies Grounded
Ice
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Glacial Systems Continental Ice Facies Grounded
Ice Diamicts
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Glacial Systems Continental Ice Facies Grounded
Ice Diamicts
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Glacial Systems Continental Ice Facies Proglacial
and Periglacial Environments
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Glacial Systems Marine Ice Facies Proximal Facies
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Glacial Systems Marine Ice Facies Distal Facies
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Glacial Systems Vertical Facies Succession
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Glacial Systems Ancient Glacial Deposits
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Deltas
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