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