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Field Techniques Final
Field Techniques Final
51
Geography
Undergraduate 3
11/21/2010

Additional Geography Flashcards

 


 

Cards

Term
What is soil?
Definition

-minerals

-organic material

-water

-air

-organisms

-laters/horizons

 

*not dirt!

Term
Soil forming factors
Definition

Climate (cl): temperature and precipitation

 

 

Parent material (pm): sediment type, mineralogy, ease of weathering

 

organisms (o): veg, micro/macro-organisms

 

typography (top): slope, aspect, erosion rates, water regime

 

time (time): old vs young soils

 

Hard to study all at the same time, so study:

-climofunction

-lithofunction

-biofunction

-topofunction

-chronofunction

Term
Soil terminology
Definition

organic horizons: litter, fermentation and humification layers (in that order)

 

Subsoil: everything between the c horizon and the organic horizons

 

a horizon: presenting an eluviation of elements

 

b horizon: horizon presenting an illuviation of elements

 

C horizon: horizon that presents comparatively no alteration compared to the other horizons

 

soil: the subsoil

Term
Soil Nomenclature
Definition

A

-heavily weathered

-max organic content

-mineral leaching (eluviation)

 

B

-concentrated leachate from A (illuviation)


C

-similar to parent material

 

MODIFIERS

h- dark, organic enriched

e- light A with eluviation (depletion) of clay, Fe, Al, organic matter

f- illuvial: accumulation of Fe, Al, organics

he- Ah horizon with eluviation

ca- CoCO3 enriched (more than parent material)

Term
Laterization/ferrallitization
Definition

Intense leaching under wet, tropical conditions

 

Rainwater dissolves primary rock minerals

 

Decreases easily soluble elements (Na, K, Ca, Mg, Si)

 

Leaves residual concentration of insoluble elements (Fe, Al)

 

Fe and Al oxidize

Term
salinization
Definition

Occurs under dry conditions, where precipitation < evapotranspiration

 

Evaporation draws moisture to the surface

 

Dissolved salts (ei NaSO4) precipitate out

Term
parent material
Definition

the underlying geological material where a soil forms

 

-geomorphic processes... landforms determine parent material

 

-controls local and regional soil formation

Term
Common soil types
Definition

CHERNOZEMIC

A:high organics (Ah)

B: minor alterations (Bm)

C: CaCO3 from A and B reprecipitates in upper parts

 

GLEYSOLIC

-prolonged water saturation (riparian areas)

-surface water concentrates in topographic lows (sloughs)

-gleying (blue-grey colours) within 50cm of surface

 

LUVISOLIC

-loamy glacial till deposits (function of PM)

A:eluvial (leached)

B: illuvial, higher clay content than A or C

 

REGOSOLIC

-young surfaces (sand dunes, floodplains, mountaintops)- little development

-B:none or thin (<5cm)

 

Solonetzic

-grassland soils

-high Na from marine shales (bedrock)

Bn: high Na content

 

****Look at pictures!!**

 

* soil over geologic time reflects stability of surfaces - can't occur with erosion or rapid deposition

Term
Soil Texture
Definition

Single most important physical property of soil

-info on: water flow potential, water holding capacity, fertility potential

 

-Soil texture is determined by the percentages of clay, silt, and sand particles in the soil.

 

-anything greater than 2mm is not part of the fine earth fraction

 

Feel Method

-set soil in hand and make a ribbon

-length of ribbon indicates clay content

-grit indicates sand/silt

-smoothness indicates silt

 

-Can also use sieve analysis

___

 

Changes in soil texture

-pedologic processes alter soil texture

-soil development (sand to silt, silt to clay, old soil has higher clay)

 

Structure, texture, grain size give additional information

-porosity

-permeability

-moisture content

-nutrient content

Term
Soil forming factors
Definition

Broad Controls

-time (development of old vs young soils)

-climate (T,P)

-organisms (overlying veg, micro/macro orgs

 

Local Controls

-parent material - sediment type, mineralogy, ease of weathering

-topography - slope, aspect, erosion rates, water regime

 

-broad controls:

1)order

2)great group

 

-local controls:

-subgroup

-family

-series

 

There are 9 orders:

-brunisolic

-chernozemic

-cryosolic

-gleysolic

-luvisolic

-organic

-possolic

-regosolic

-solonetzic

Term
calcification
Definition

-low rainfall

-CaCO3 leached from A (easiest to dissolve in H2O)

-re-precipitates in B (Bca) when moisture evaporates

Term
podzolization
Definition

-cold, humid, coniferous, (acidic)

 

-rainwater leaches acidic litter (Fe, Al, oranics leach from A) (bleached-grey A)

-B horizon: concentrated Fe, Al, organics

Term
Detailed soil profile data
Definition

-color

-structure

-texture

-effervescence

-unusual features

Term
Soil Color
Definition

-tells about organics, eluviation, minerals, etc

-use Munsell colour chart

 

HUE:

-relation to red, yellow, green, blue, purple (top right corner)

 

VALUE:

-lightness (0= absolute black; 10= absolute white)

-up and down

 

CHROMA:

-strength

-0= neutral greys

-side to side

Term
Soil Structure
Definition

-particles adhere in specified shapes

-"structural peds"

-named based on appearance

 

-peds form by et/dry, freeze/thaw processes

-held together by clay, organic matter

 

TYPES
-granular

-platy

-sub-angular blocky

-prismatic/columnar

 

 

GOOD STRUCTURE = HEALTHY SOIL

Term
Properties of Sand/Silt/Clay
Definition

Sand Properties

-feels gritty

-non-cohesive

-high porosity

-well-drained

-fewer nutrients

 

Silt Properties

-floury, smooth

-not sticky (plastic, malleable when wet)

-retains more water, nutrients

-highly erosive (partly due to particle shape)

 

Clay Properties

-sticky, plastic

-moldable when wet

-small pore spaces

-highw ater adsorption

-shrink swell process

-flat plates, flakes

-small particles = colloids

-will not settle from suspension

-contaminants

Term
Stratigraphy (What, How?, Why?, Qs to Answer, Qs to ask)
Definition

Composition, sequence, classification, spatial distribution, and correlation of stratified rocks/deposits

 

stratigraphic discontinuity: change in color, hardness, structure, etc.)

 

How?

-stratigraphic sections

-well logs

-sediment cores

 

Why?

-Past surface processes

-weathering, deposition, life, uplift, climate

-relationships between rock layers

-interpretation of depositional environment

 

-Paleogeography, biology, sea-level and climate, plate techtonics

 

QUESTIONS TO ASNWER

1)How old?

2) Eents that produced the section? In what order?

3)Environment when these rocks were deposited?

 

QUESTIONS TO ASK

1)Sediment sources

2)sea-level change

3)plate tectonics and internal earth processes?

4)changing biosphere

Term
Sedimentary stratigraphy
Definition

Depositional history: litho-

Organism evolution: bio-

Earth composition: chemo-, litho-

Plate tectonics: magneto-, litho-, bio-

Climate: chemo-

 

Facies

"distinctive rock that forms under certain conditions of sedimentation, reflecting a particular process or environment"

 

sedimentary facies = depositional environment

biofacies = fossil content

lithofacies = grain size, mineralogy

 

___

with increasing ocean depth, go from sandstone facies to shale facies to limestone facies

Term
Stratigraphic principles
Definition

1) Original horizontality (sedimentary layering)

-at some point, they were horizontal

 

2)Superposition (young over old)

-superposition of layers (strata)

 

3)Cross-cutting relationships (intrusions, faults)

 

4)Faunal and floral succession

Term
Walther's Law
Definition

Only facies that occur side-by-side (laterall) can be vertically superimposed on each other

 

Ie.

Seal level rise (transgressive)..

-limestone on top, then shale, siltstone, andstone

 

Sea  level decrease (regressive) ..

-other way around

 

-will always be in that order

Term
Materials for logging sections in the field
Definition

-tape measure

-grain size card (roundness, sorting)

-sample bags and marker

-ruler

-brunton compass

-calipers

-trowel

-geological hammer

-notebook

-camera

-shovel

Term
Methods for logging sections in the field
Definition

OVERVIEW

-GPS location

-Site notes:

---orientation, dimensions

---relationship to nearby features

---part of a larger landform?

-field sketch of exposure

-boundaries between units sharp or dicontinuous?

 

POINTS TO CONSIDER

-How many large-scale units?

-lateral continuity of beds/units

-any deformation?

-photograph with a reference object (for scale)

-true section or slump?

 

DETAIL

-colour

-organic content

-sediment texture

---particle size and sorting

-sediment lithology

---clast shape and roundness

---lithology

-bedding (beds, lamina)

-sedimentary structures

---deformation

---faults

-Sampling

---particle size, chemical properties, etc

Term
watch geomorph refresher movie: http://faculty.gg.uwyo.edu/heller/sed_video_downloads.htm#Kempema%20anchor
Definition
Term
Stratigraphic Elements
Definition

If you see crazy things, it could be due to a land process (rockslide) of maybe missing information (ie. loss of time)

 

**look at pictures of all these

 

1) Parallel laminations

-upper and lower contacts are approximately parallel

-can result from:

---settling from suspension

---deposition in a low energy enviornment

---laminar flow

 

2)Ripples

-indicate past presence of water

 

3)Cross bedding

-higher energy means ripples migrate

-continuous erosion on stoss side, deposition on lee side causes cross bed formation

 

4)Tabular cross bedding

-high flow, flow decreases, then high flow again

 

5)Graded bedding

-when particles become progressivle finer (FU) or coarser (CU) from bottom to top

-coarse means high energy, fine means low

 

6)Varves

-a true varve= a couplet of summer silt and winter clay

-can count years

 

7)Mud cracks

 

8)Matrix vs clast -supported sediments

 

9) Soft Sediment Deformation

glaciotectonics: deformation of sediments by moving ice

 

***We can say very little about a sediment/tectonic structure without the landscape setting

-need an integrated approach

 

Term
Why Date?
Definition

Stratigraphic sections

 

Lace cores

 

Glacier Fluctuations

 

Landform development

Term
Dating Techniques?
Definition

Numerical Age

-Carbon14

-luminescence

 

Relative age

-weathering rind

-lichenometry

-dendrochronology

-varves/ice cores

-biostratigraphy

-ashes

 

Mixed Techniques

-palynology

Term
Numerical Dating
Definition

14C

-radio-isotopes (14C, U, K, etc)

-compare present 12C/13C/14C ratio with dead or fossilized organic material

-half-life of 14C is 5730 +/- 40 yrs

-works up to ~30kyrs (max 60kyrs)

 

Luminescence

-Radiation damages minerals (ie quartz) and creates electron traps in the crystals

-stimulated until released

-types are thermoluminescence, optical-(visible light), infrared, and radio (ionizing radiation)

-timeframe is 100s of thousands of years

Term
Processes of chemical alteration (Relative dating)
Definition

-weathering rinds (freshly exposed rock develops rind)

-calculate mean rind thickness for single lithology

 

-pedogenesis/paleosols

Term
Incremental methods of relative dating
Definition

LICHENOMETRY

Rhizocarpan geographicum is most commonly used

-grows ~1-4mm/yr

-invade quickly on bare rock (cemetary grave stones have exact dates)

-compae with calibrated lichen size with lichen @ field site

-grow rates vary with elevation, aspect, rock type, proximity to sea, and time

 

Dendrochronology

-based on analysis of tree-ring growth patterns

-landslides, glacier fluctuations, floods, droughts, volcanic eruptions, fire, etc

-sample live trees, analyze/correlate with dead stumps, relate to specific events

 

Varve chronology

 

Annual layers in glacier ice

 

 

Term
Relative Dating (3): Age-equivalent stratigraphic markers
Definition

Tephrachronology

(using volcanic ash)

-types are mafic (local tephras; not explosive) and felsic (cascades, indonesia... explosive and widespread tephra)

-recent technique used since 40s in N America

-St Helens erupted 3500BP and 1980

 

Palynology (mixed dating)

-pollen analysis

-use microscopic analysis to determine pollen types from sediment cores

-numerical dating

 

Paleomagnetism

Term
Summary of dating methods
Definition

Dating methods most valuable when calibrated/cross correlated to provide dates in years

 

Certain methods only usable for particular materials within a certain age range

 

Use of more than one technique ives you a more reliable chronology

 

Challenge is to improve techniques of old methods and develop new ones

Term
Snow properties
Definition

Can be thought of as a soil (particles and pore space)

 

Cold snow (<0), pore space filled with air

When melting, some have water (only get runoff when all pore spaces are full)

-characterized using many variables

 

VOLUME

Vs = Vi + Vw + Va = hsA

hs=depth snow, A=area(surface), s=snow,i=ice,w= liquid water, a=air

 

POROSITY

=(Vair+Vw)/Vs

-ratio of pore volume to total volume

 

SNOW-WATER EQUIVALENT

amount of water from melting snow (given in a depth)

hm= (ps/pw)*hs

-determines water that ultimately enters hydrological cycle

Term
Snow Metamorphism
Definition

Caused by:

 

GRAVITATIONAL SETTLING

-increased weight and increased temp = increased metamorphism

-decreased density = decreased metamorphism (because dry and cold)

-density increase 2-50kg/m3/day in shallow snowpack

-

 

DESTRUCTIVE (equitemperature) METAMORPHISM

-points, projections evaporate and necks form

-towards larger and rounder snow crystals

-stronger snow pack

 

CONSTRUCTIVE (temp gradient) METAMORPHISM

-creating new crystals (very faceted)

-grains enlarge (no necks)

-angular crystals, depth hoar (form at base of pack)

-weaker snowpack (slab avalanche)

 

MELT METAMORPHISM

-refreezing of liquid H2O in snowpack

-release of latent heat (can warm up, even though freezing)

-ice lenses, large snow grains

-ie. chinooks or in spring

Term
Snow terminology
Definition

Precipitation

Snowfall

Snowpack

Snowmelt (doesn't mean runoff)

Ablation

Water output (runoff)

Term
Glaciers- background & why study?
Definition

Distribution is global, though Canada has a high concentration

-There are different types! (alpine, arctic)

 

Outburst floods: Icland

-colvanic melting (break through glaciers, or come out somewhere else)

-landslide prevents melt, then breaks through

 

Salmon: mid-coast BC

-water supply: southern AB

-tourism

-climate change

-hydropower

-sea level change

-land surface albedo change (feedbacks)

Term
Climate change and variability
Definition

IPCC 2007

Predictions?

-temperature, precipitation


Sea level change controversy

-tied to glaciers

 

Variability is where the mean value stays the same

Change is where the mean changes

 

Changes are occuring in both glacier area and thickness!!

 

In alpine glaciers, we will always see a change in extent associated with a change in thickness. In arctic glaciers, changes in only thickness can happen.

Term
Glaciers and Satellite Imagery
Definition

Changes in area and volume

 

advantages of satellite imagery over field work..

1)cheaper

2)more area covered

3)repeat visits

Term
Mass Balance
Definition

b = c + a

balance = accumulation plus ablation

-based on calandar year or balance year (usually sept-aug)

 

ACCUMULATION

-Snow

-Avalanches

-Superimposed ice (only on polar, sub-polar glaciers- melts then refreezes without runoff)

 

ABLATION

-melt/runoff

-calving

-evaporation

-sublimation

 

 

Accumulation vs ablation zone drives ice dynamics

Usually, accumulation zone feeds ablation zone

Term
Measuring Mass Balance
Definition

1) DIRECT measurement

-snow pits, UDG, snow stakes

-ablation stakes

-winter(bw) vs summer (bs) balance

-stratified sampling by elevation and distribution to edges

 

2)Remote Sensing

-imagery

-radar or laser altimetry

 

3)Indirect Methods

-Hydrological method (Bn = P-R-E)

-Climatic calculation (energy balance)

 

DECLINING MASS BALANCE

-climatic drivers

-dynamics (thinning vs retreat)

-hydrology

 

Climate change AND variability (coming out of ice age) affecting glaciers today.

Term
Measuring Snow and Snow Melt
Definition

Measuring Precip

-use standard gauges (same as rain gauge)

-problems /w wind though


MEASURING SNOWFALL

Standard Method

-ruler on a board

 

Doppler radar

-can be problems due to radar feturn from interfering objects

 

MEASURING SNOWPACK

SNOW PITS

-Dig a pit facing South

-identify individual layers

-collect continuous density profile

-collect temperature profile

-assess crystal structure

 

SNOW STAKES

-givs depth, not density

-measure surface height on fixed ruler

-labor intensive

 

SNOW SURVEYS

-several snow courses, 150-250m long

-6+ points each course (every ~30m)

-several in a water shed

-sample using a snow tube, get depth, mass

-labour intensive also

 

AUTOMATED

Acoustic Gauges

-measure using ultrasonic rays (UDG or SR50)

 

Radioactive Gauges

-gamma-ray source inserted at land surface, detector hanging above

-determine snow thickness, water content from ray attenuation

 

Radar

-shows internal structure of snowpack

-can measure large area

 

Snow Pillows

-weight of snow on liquid filled bladder pushes float up tube, indicating SWE

-require lots of maintenance

 

LARGE SCALE MEASUREMENTS

Airborne Microwave Sensing

-measure passive microwave emissions from snowpack

-SWE, areal extent

 

Airborne Radar

-beam radar snowpack and record return signal

-snow stratigraphy, liquid water content, SWE

-only works in flat terrain

 

LiDAR is newer technology, with potential to work in complex terrain

 

SATELLITES

-visible infrared and microwave

-clouds vs snow is a problem

-no volume, just extent

 

SNOW MELT

-lysimeters (problem is freezing)

-snow pillows (can't tell differnece b/w melt and sublimation)

-pans (looking @ individual events)

 

Term
Stratigraphic Correlation
Definition

*Look at series of sections, not just one

 

There can be lateral changes in bed thickness

 

Unconformities can cause a hiatus, which represents lost time (stratigraphically complete vs incomplete)

Term
Principle 4: Fossil Record
Definition

Index Fossils

 

Relative dating methods

-stratigraphic dating

-ice cores

-varves

Term
Sedimentary Rocks
Definition

-75% of global exposed surface rock

-exposure due to elements weathering sedimets

 

What Are They Made Of?

-particles from existing rocks and biological remains

autochthonous - originate within the basin where they accumulate

allochthonous - originate outside the basin where they're deposited

 

Autochthonous

-particles in situ

Group1: precipitates

-crystallization from liquid (limestones, evaporites)

 

Group2: organics

-carbon rich residue (coal)

 

Group3: Residuals

-remain after intense weathering

-often iron/aluminum (low solubility)

-bauxite (aluminum ore)

 

Allochthonous

-particles transported

 

Group1: Terrigenous

-directle from weathering (clay[shale], silt [siltstone], sand [sandstone], gravel [conglomerate]

 

Group2: Volcaniclastic

-Igneous particles transported/deposited by wind, water

-tephra, ash, tuff

 

HOW ARE THESE PARTICLES CREATED?

Weathering and Erosion

-frost

-salt

-chemical

-soil creep

-mass wasting

-surface erosion

 

HOW TRANSPORTED?

-water

-wind

-gravity

-ice

Term
Lithification
Definition

Unconsolidated materials becoming rock

-called diagenesis (or lithification)

 

Basic processes:

 

-physical (compaction)

-chemical (cementation).. quartz

-biological (bioturbation).. rearranges particles.. ie. worms disturbing

 

Cementation: volume @ A = Volume @ E (filling pore space)

 

Compaction = not equal (removing pore space)

Term
Stratigraphy- what to look for in the field
Definition

DEPOSITION TYPE

Fluid flow...

-laminar (transfer of mass and momentum)

-turbulent (no mass transfer b/w layers)

 

Sediment moves through layer through suspension, saltation, and rolling/sliding

 

Bedform Formation (sand-bedded systems)

-lower and uppoer flo regimes

-lower flow regime  creates dunes at high velocities

-upper flow regime creates antidunes and higher flow velocity

 

GRAIN SIZE

-large range... log scale most practical

-grain size histogram can be linear or logarithmic

-linear is heavily positively skewed

-logarithmic is more normally distributed

 

GRAIN SORTING

-can be poor, moderately or well sorted

 

GRAIN SHAPE

-Roundness (degree of abrasion; sharpness of edges and corners)

-Sphericity (how close to the shape of a sphere; length/width/thickness)

Term
Designing Fieldwork considerations
Definition

1) Scientific Method

 

2) Where, What, How, Timing?

 

3)Safety, permission

 

4)Cost, logistics (access, wildlife)

 

5)Examples

Term
Scientific Method (9)
Definition

1) Identify Problem

 

2) Formulate Hypothesis

 

3) Develop Research Plan

 

4) Select Field Site

 

5) Prepare Data Collection

 

6) Collect Data

 

7) Analyze Data

 

8)Draw Conclusions

 

9)Report Results

Term
Fieldwork: Where? How? Questions to Consider(5), correct procedures, and Don't forget(4)
Definition

Where?

Location>Lanscape>Niche

 

How?

1) Map/measure/sample observable features and materials

 

2) Use instruments to monitor and measure processes

 

3)Interview to understand non-visible aspects of the area (asp helpful /w arctic research)

 

QUESTIONS TO CONSIDER

1)How do we perceive things?

2)How do our minds use the images we see (brains process diferently)

3)What are we doing when we interpret what we see? (remembering? fairly subjective...)

4) What is spatial reasoning?

5) What are we doing when we think spatially

 

CORRECT PROCEDURES

Observe/Measure Systematically ***

 

Think in SYSTEMS***

 

***OFten get different results from same data***

 

 

Don't forget!!

-safety

-permission

-cost

-logistics (practicality of site)

Term
What is Landscape Analysis?
Definition

Holistic assessment of a suite of environmental processes across scales

 

Process-form Relationships

 

-Sediment/soil properties

-characteristics of specific features (lake, dune, glacier, etc)

-physiographic/tectonic setting

-hydroclimatic setting

 

USEFUL FOR REGIONAL-SCALE STUDIES!

-Reveal patterns and processes of complete cycles: climate change, tectonics, etc

-Complement short-term studies of modern environments

Term
Linking Past and Present (landscape analysis)
Definition

Reconstruction of geographic environments is based on observations and assumptions

 

Present is key to past!

 

1)Need to correct contemporary analogues

 

2)greater knowledge of modern systems results in less errors in understanding past systems

 

*largest scale = largest errors

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