Distribution and Spatial Interaction

• Distribution – arrangement of feature in space…properties of distribution…

o Density: frequency something occurs

• Arithmetic Density: total # of objects in an area (i.e. pop density – 340/sq km)

• Physiological Density: # of persons per unit of area suitable agric (i.e. can country feed itself?)

World Population Density

Distribution (cont’d.)• Concentration: feature’s spread over

spaceo Clustered/agglomerated: objects

close togethero Dispersed/scattered: objects far

apart (see next slide)

• Pattern: geometric arrangement of objects in space (square, rectangle, irregular, etc.)

Density and Concentration of

Baseball Teams, 1952–2000

The changing distribution of North American baseball teamsillustrates the differences between density and concentration.

Time Space Convergence

• Time-space convergenceo The rate at which places move closer together

in travel or communication costso Results from a decrease in the friction of

distance as space-adjusting technologies have brought places closer together over time

• Global and local• Shrinking of space has important

implications

Time-Space Convergence• Friction of distance – Tobler’s 1st Law of Geog:

everything is related to everything else, but nearer things are more related than distant things (i.e. distance itself hinders interaction).

• Leads to distance decay: contact between two places decreases as distance increases

Discuss• How much is Distance Decay an issue today? Is

this something geographers might have to re-think?

Quick Write: Think about where people are spaced in the US. Where are they clustered? Why there? Where is it dispersed? Why?

Space-Time Compression

1492–1962

The times required to cross the Atlantic, or orbit the Earth, illustrate how transport improvements have shrunk the

world.

Spatial Interactiono Complementarity: we need each other

• Ex. One area needs houses, other area has the trees for lumber

o Transferability: cost involved in moving goods from one place to another• Cost• Ability to bear the costs• Variability• Space-Time Compression (see next slide)

o Accessibility: is location accessible? Highways, RR, shipping? Ex: food very expensive in Alaska

DIFFUSION • Process in which phenomenon (disease, trends,

technology, etc.) spread from one place to another over time

o Hearth: place of origination

o Diff happens quickly today w/ modern technology, communication, transportation

o The “S” Curve

Types of Diffusion

• 1.) Relocation Diff: spread b/c people move• Languages, Money, Aids

• 2.) Expansion Diff: snowball processo A. Hierarchical diff: top down process• Fashion, Music

o B. Contagious diff: like a wave without regard to hierarchy• Diseases, Fads

o C. Stimulus diff: spread of underlying principle, even though characteristic itself failed to diffuse• Settlers in America – tobacco growers

Hierarchical Diffusion

Contagious Diffusion

Hierarchical and Contagious

Stimulus Diffusion