ENVS 203 Physical Geography

Biome

A large-scale ecosystem with relatively uniform vegetation, driven by climate

Tropical Rainforest

Rainy, warm all year; Near ITCZ and subsolar point; High biodiversity

Tropical Seasonal Forest

Warm all year (Near subsolar point) with a distinct wet and dry season (shifting ITCZ and monsoons)

Tropical Savannah

Warm all year (Near subsolar point) with seasonal rainfall (shifting ITCZ and monsoons) and grassland vegetation. Open landscape: fire, grazing

Mediterranean

Temperate (mid-latitude, not far inland); Dry sumers (subtropical high); Vegetation drought and fire adapted - low shrubs

Desert

Arid, cold or hot, subtropical high, rainshadow, spaced vegetation = water stress

Temperate Grassland

Continental climate; Arid (rain shadows, continental, subtropical high); Mostly converted to agriculture or rangeland - most modified biome

Temperate Rainforest

Maritime mid-latitude; Usually west coasts (subpolar low); Humid winters, dry summers (subtropical high)

Tundra

High latitude or high elevation; Small shrubs and herbs, very short growing season; Cold and dry

Glacier

a large mass of ice formed from the accumulation of snow, showing evidence of movement

Glaciar formation

Snowflakes, time, and pressure; Snow → Granular Ice → Firn → Glacial Ice

Glacial mass balance

Winter accumulation vs. summer ablation

Glacial input

Snow

Glacial output

Melt water or water vapor

Neutral mass balance

Equal input and output

Positive mass balance

Snowfall exceeds ice loss; Glacial advance

Negative mass balance

Snowfall less than ice loss; Glacial retreat

North Cascades Mass Balance

~30% volume lost since 1984, ¾ will melt this century

Glacial Erosional Feature: U shaped valley

Glaciers erode sides and bottom

Glacial Erosional Feature: Fjord

Flooded glacially carved valley

Glacial Erosional Feature: Hanging valley

Left where a tributary glacier valley feeds into a larger, deeper trunk valley

Glacial Erosional Feature: Cirque

Bowl shaped depression with steep sides

Glacial Erosional Feature: Tarn

Mountain lake that forms within or below a cirque

Paternoster Lakes

Series of tarns connects by drainage passage

Glacial Erosional Feature: Aretes

Knife-like ridge formed between cirques

Glacial Erosional Feature: Horns

Steep pyramidal peak formed from 3+ cirques

Glacial Depositional Feature: Glacial Till

Unsorted sediement deposited directly by glacier

Glacial Depositional Feature: Moraine

Glacially deposited piles of sediment

Lateral (sides)

Medial (center)

Recessional (during retreat)

Terminal (downslope edge)

Glacial Depositional Feature: Erratics

Rock deposited by glacier. Strange locations, don’t match size and type of local rocks; evidence of past glaciation in that spot

Glacial Depositional Feature: Kettle Lake

Ice blocks buried by sediment melt and form pond

Soil Forming Factors

CLimate Organisms Relief Parent material Time

Soil Forming Factors: Climate

Development rates: Higher in warm, wet; slower in cold, dry

Weathering rates

Leaching

Soil Forming Factors: Organisms

Nutrient input and cycling

Soil Forming Factors: Relief

Topography; steep=shallow soil, flat=deeper soil

Soil Forming Factors: Parent material

Greatest impact on young soil

Soil Forming Factors: Time

All other factors require time to operate

Young=resembles parent material, Mid-age=usually most fertile, Old=less fertile, leached

Soil Horizons

Top to bottom: O, A, B, C, R

Soil Horizon O

Organic, 0-2”, leaf litter

Soil Horizon A

Top soil, major nutrients, dense rooting, 4-18”

Soil Horizon B

Clay rich, no organic material, generally infertile, “deep” - varies

Soil Horizon C

Unaltered parent material

Soil Horizon R

Regolith - unweathered bedrock

Andisols

Formed on volcanic ash; Not highly weathered; Moderately fertile, good water holding capacity; <1% global soils, locally important in pacific rim regions

Aridsols

Dry soils; Soil moisture high enough to support plant growth no more than 90 consecutive days/yr

Mollisols

Dark soft grassland soil; Great plains; Soft even when dry; Most productive soil; 22% of US

Oxisols

Most highly weathered, good infiltration, leads to nutrient leaching; Hot climate, year round moisture, and many decomposers means fast nutreint release, superficial root depth; Very fast nutrient cycling at surface; Deep; Fragile if disturbed; Rainforest regions of S. American and Africa

Spodosols

Coniferous forest soils; Strongly acidic; Cool and wet climate; Typical NW forest soil; Leached (white E horizon)

Entisols

Young soil without distinct horizons; Lacking time; Typically found in disturbed areas

Gelisols

Young soils with minimal horizon development; Frozen part/all year

Drainage basin/Watershed

Geographic region drained by a trunk stream

Discharge

Volume of water flowing past a fixed point within a stream channel

Q = depth x width x velocity

Hydrograph

Discharge over time

Baseflow

The stable portion of a river’s discharge, largely maintained by groundwater inputs, especially during dry periods

Velocity and flow characteristics

Velocity depends on amount of friction, more friction along channel bed, banks, and obstacles.

Discharge relationship to glacierized vs. unglacierized watersheds

Glacierized watersheds create more stable discharge, peaking in summer with meltwater. Unglacierized watersheds have more seasonal variability and low discharge in summer

Discharge response to rain

Lag between precipitation and discharge; Depends on soil type, topography, size of drainage basin, and type of drainage network

Straight River Channel

Tend to be unstable, most persistent straight channels controlled by humans; Velocity fastest in center, just below surface

Meandering River Channel

Curving channel, typically on large rivers, flat or gently sloping landscapes

Braided River Channel

Consists of smaller individual channels that shift as erosion/deposition occurs on sides, braiding increases as gradient decreases

Point Bar

Where deposition is occuring, inside curve

Cut bank

Where erosion is occuring, outside curve

Oxbow lake

Meandering river's curve gets cut off from the main channel

Meander scar

A crescent-shaped or horseshoe-shaped dry bed or depression in the landscape that is left behind after a meandering river's old path is cut off and the resulting oxbow lake dries up

Sediment deposition in a dam’s reservoir: where does it occur? Why? What do we call
the feature left behind after a reservoir is drained?

Sediment builds up to form a delta in the back as the front water becomes stagnant - stream deposits all sediment in transport into alluvial terrace.

Alluvium

Charactertistically well sorted and stratified

Colluvium

Material deposited by gravity, angular and unsorted

Sediment Transport: Dissolved load

Dissolved minerals, salts

Sediment Transport: Suspended load

Fine grained; turbulence

Sediment Transport: Bed load

Coarser; rolling, bouncing on bed