Chapter 4: Physical Measurements

Daniel R. Montello and Paul C. Sutton

Learning Objectives

  What are physical models and how are they used in geography?

What are representative types of physical measurements

Physical Measurements

 Physical Measurement: collecting data by recording physical properties of phenomena at or near the earth surface   Major type of data collection in physical geography Also used by human geographers: collect “physical traces” or “residues” left behind by human behavior or activity

Physical Measurements in Physical Geography   Historically, physical geographers have been interested in the earth as the home of humanity.

Issues with field research in physical geography:  Site accessibility  Transportation to and from site

Physical Measurements in Physical Geography  Collecting data away from field settings:   Simulations  Physical models  Environmental cabinet Computational models  Airplane, satellite remote sensing

Geodetic Measurement

  Three methods of data collection:  Aerial or satellite imagery (remote sensing)   From existing geodetic databases Directly in the field (ground surveying) With GPS, laser range finders, and other electronic tools, supplanting of older technologies by newer ones has occurred dramatically in the last few decades.

Physical Measurements of Earth Systems   Four earth systems:     Lithosphere (geosphere): terrestrial earth surface Atmosphere: the envelope of gases and other materials surrounding the terrestrial surface Hydrosphere: the water bodies (liquid, gaseous, and solid form) Biosphere: the living earth of plants, animals, fungi, microorganisms, etc. All these systems are deeply interrelated

Physical Measurements of Earth Systems  Specific topics (lithosphere):  Geomorphology: description and explanation of the shape or form of earth surface landforms    Orogenesis: mountain formation processes Denudation: landform degradation processes Soils: dynamic layer on the earth surface  Influence agricultural patterns strongly, which influence many human patterns

Physical Measurements of Earth Systems  Specific topics (atmosphere):  Climate  Insolation: Intercepted solar radiation   Weather Paleoclimatology: climate history  Proxy measures:   Dendrochronology Pollen analysis   Ice coring Ocean, lake sediment analysis

Physical Measurements of Earth Systems  Specific Topics (radiocarbon dating):  Based on the fact that a small proportion of atmospheric CO2 is radioactive (includes 14C instead of 12C) and becomes incorporated into living creatures at equilibrium concentration. When an organism dies, 14C concentrations decay at a predictable rate, providing a basis for measuring the age of the material.

Physical Measurements of Earth Systems  Specific Topics (hydrosphere):  Hydrometry: measurement of water flow in river and stream channels  Ocean currents: distribute energy, nutrients, and pollutants around the planet  Drifters: GPS track drifter paths, and therefore current path

Physical Measurements of Earth Systems  Specific topics (biosphere):  Counting: the major form of physical measurement  Sometimes dependent on netting and trapping, which can have ethical consequences  Vegetation: Observed, counted, and measured in the field

Physical Measurements in Human Geography   Usually observations are residues of past activities that are not intentionally created as data Reactance: when people’s behavior changes because they are aware of being measured or observed

Physical Measurements in Human Geography    Intentional: a transportation board puts traffic lights and stop signs at some intersections and not at others Unintentional: bare spots in a yard indicate areas of high usage Three actions of physical traces:    Accretions: an addition, deposition, or accumulation Deletion: a removal, erasure, or obliteration Modification: a change, alteration, or conversion

Physical Measurements in Human Geography  Four types of functions/purposes:  Byproduct of use: bare spots left in a yard    Adaptation for use: children making openings in fences to create more direct routes Display of self: design of a front yard Public message: road signs or graffiti