Physical Geography

Citation

Patrich, J. (2023). Physical Geography (Version 2; T. Radtke, Ed.). College of the Canyons. Free official edition: https://drive.google.com/drive/folders/1oTVcpLRpb9YYHCxMp_UdzFHOxTL-Pj2G

Chapter Summary

The book is an open educational resource of about 300 pages, written and compiled by Jeremy Patrich for the physical geography course at College of the Canyons, a California community college, and licensed CC BY 4.0 unless otherwise noted. It is divided into nineteen units. Each opens with a list of goals and objectives and closes with a unit summary; in between, the text is illustrated with many photographs, diagrams and tables, a good number of them taken on the author's field trips with students. The preface describes "Pin It!" boxes for points to remember, and the units contain QR codes and links to the author's videos, including field visits to the San Andreas Fault and Death Valley. There are no end-of-unit questions, glossary, index or reference list.

Unit 1: Introduction to Geography as a Discipline

Defines physical geography as the spatial study of Earth's lands, waters, living things, atmosphere and interior, then discusses scientific and geographic inquiry and the scientific method. It then introduces the geographic grid and surveys remote sensing, GPS and GIS.

Unit 2: Earth's Place within the Cosmos

An astronomy unit: the expanding universe and the Big Bang, star systems and galaxies, the Milky Way, nuclear fusion in stars and the classification of stars.

Unit 3: Introduction to Geology & Geologic Time

Explains what geology is, then builds a sense of deep time through the principles of stratigraphy, uniformitarianism and the geologic time scale. It distinguishes relative from absolute dating and explains radiometric dating and its assumptions.

Unit 4: Mapping Earth's Surface

A cartography unit covering map scale (including representative fractions and scale bars), contour lines on topographic maps, extent versus resolution, the mechanics and distortions of map projections, and the U.S. Public Land Survey.

Unit 5: Earth-Sun Relationships: Reasons for the Seasons

Earth's rotation and revolution, solstices and equinoxes, solar angle and day length, and perihelion and aphelion. The unit also covers solar radiation, the greenhouse effect and greenhouse gases, and eclipses, lunar phases and tides.

Unit 6: Earth's Atmosphere

The composition and layers of the atmosphere, the relationships between energy, heat and temperature, the solar budget and albedo, and global atmospheric circulation. Local winds are illustrated with the rain-shadow effect and California's Santa Ana winds.

Unit 7: Elements of Weather & Climate

Atmospheric moisture, air masses and fronts, mid-latitude cyclones, thunderstorms and other extreme weather. The unit then separates weather from climate, presents the five main groups of the Köppen classification in a table, and briefly discusses climate change, global warming and the monitoring of climate.

Units 8–11: Basic Mineral Development; Igneous Rocks; Sedimentary Rocks; Metamorphism & Metamorphic Rocks

Four units on Earth materials. Unit 8 covers atoms, ions and the identification of minerals by their physical properties. Unit 9 introduces the rock cycle, magma composition, crystallisation (the Bowen reaction series) and igneous textures. Unit 10 classifies clastic and chemical sedimentary rocks and uses sedimentary structures and fossils to interpret past environments. Unit 11 treats the factors controlling metamorphism, foliation, the classification of metamorphic rocks and their links to plate tectonics.

Unit 12: Weathering & Soils

Mechanical weathering (including frost wedging), chemical weathering by hydrolysis, oxidation and dissolution, mass wasting and landslide hazards, and soil formation, texture and horizons.

Units 13–15: Earth's Dynamic Surface: Plate Tectonics; Earth's Dynamic Surface: Tectonics Force; Earth's Dynamic Surface: Volcanoes

Unit 13 covers Earth's interior, continental drift and seafloor spreading, and the types of plate boundaries. Unit 14 explains tectonic stress, folds and faults, earthquakes, magnitude and intensity, shake maps and liquefaction. Unit 15 relates magma formation to tectonic settings and explains how magma composition controls eruption style, the main types of volcanoes and volcanic hazards.

Units 16–19: Shaped by Coastal Processes; Shaped by Rivers & Running Water; Shaped by Wind as a Geomorphic Agent; Shaped by Glaciers

The geomorphology sequence. Unit 16 covers waves, longshore drift, erosional and depositional coastal landforms, sea-level change and human interference with shorelines. Unit 17 treats drainage basins, graded streams, stream erosion and deposition, and then water storage in lakes and groundwater. Unit 18 defines degrees of aridity and describes wind erosion, dune types and other desert landforms. Unit 19 reviews Earth's past glaciations and the Milankovitch cycles before describing how glaciers work and the landforms of glacial erosion and deposition.

Key Concepts

Units 1–5: Foundations

• Geographic grid: latitude and longitude as angular measurements used to fix location.
• Geospatial technology: remote sensing, GPS and GIS for collecting and analysing spatial data.
• Map projection: a systematic transformation from globe to plane that always distorts some property.
• Reasons for the seasons: the tilt of Earth's axis and its orbit, which change the angle and duration of sunlight.

Units 6–7: Atmosphere, Weather and Climate

• Albedo and the solar budget: the share of incoming energy reflected, and the balance of energy into and out of the Earth system.
• Air masses and fronts: large bodies of air with uniform temperature and humidity, and the zones where they meet.
• Köppen classification: five main climate groups defined by temperature and precipitation.

Units 8–12: Earth Materials and Weathering

• Rock cycle: the processes linking igneous, sedimentary and metamorphic rocks.
• Chemical weathering: hydrolysis, oxidation and dissolution of minerals that are unstable at the surface.
• Soil horizons: layers that develop with depth as climate, parent material, slope and time act on weathered rock.

Units 13–19: Tectonics and Landforms

• Plate boundaries: divergent, convergent and transform margins and the activity at each.
• Longshore drift: sediment moved along a coast by waves arriving at an angle.
• Graded stream: a stream whose long profile has adjusted to a smooth curve, and which can lose that state through uplift or a change in base level.
• Glacial landforms: U-shaped valleys, arêtes, horns and hanging valleys from erosion; till, eskers and outwash from deposition.

Critical Analysis

Strengths

• Free and openly licensed. The whole text, also in a Word version, can be downloaded at no cost and adapted under CC BY 4.0.
• Clear unit structure. Every unit states its goals at the start and summarises at the end, so a student can check what each unit expects. Units are short (roughly 2,400 to 6,300 words) and largely independent.
• Field-based and regional. Many photographs come from the author's field trips, and the examples draw heavily on California: the San Andreas Fault, Death Valley, Yosemite, the Sierra Nevada, the Mojave, Mono Lake and the Santa Ana winds. Linked videos show the author in the field, which helps distance learners.
• Strong on geology and landforms. About half the book deals with Earth materials, tectonics and geomorphology, with detailed treatment of rock types, volcano types, earthquakes, coasts, rivers, deserts and glaciers.

Limitations

• Gaps in coverage. There is no unit on the biosphere, biogeography, biomes or ecosystems, and oceans appear only through waves and coastal processes. Reviewers on the Open Textbook Library (Dimitar Dimitrov in 2021; Jackie Gallagher and Justin Hartnett in 2024) all point out the missing biosphere and the thin treatment of hydrology; Gallagher adds that world climates are introduced but not described, with no climographs.
• Weighted towards geology. Four units on minerals and rocks and a unit on astronomy take space that many physical geography courses give to climate regions and vegetation. Hartnett questions the place of Unit 2 in the course.
• No study apparatus. There are no review questions or exercises, no glossary, no index and no references for further reading, points also raised by Dimitrov and Gallagher. Some figures and tables are credited to other open sources (for example, tables by Steven Earle), and a few cross-references point to chapters that do not exist in this book, such as an "Erosion and Deposition chapter" and "Chapter 10" for continental drift.
• Some figures need checking. A few statements are dated or loose; for example, the greenhouse-gas comparisons in Unit 5 use older values for the warming power of methane.

Where It Fits in the Course

Patrich's book is the free, short entry point to this course. Alan Strahler's Introducing Physical Geography is a much longer commercial survey that covers what Patrich omits, with full chapters on global climates, biogeographic processes, global biogeography and soils; students using Patrich as their main text can borrow those chapters. Christopherson and Birkeland's Geosystems is a fuller systems-based textbook organised around the atmosphere, hydrosphere, lithosphere and biosphere, with sustained attention to climate change and human impacts.

For deeper study, Smithson, Addison and Atkinson's Fundamentals of the Physical Environment explains the processes behind climate, landforms, soils and ecosystems in more depth than a first-year survey, and Hartmann's Global Physical Climatology is a quantitative treatment of climate physics. Patrich is best read first or alongside one of the larger texts.

How to Use This Book

The book suits first-year students in introductory physical geography or earth science, especially at community colleges and in online courses, and needs no background beyond secondary-school science.

A practical plan:

• Core: Units 1 and 3–7 for location, maps, time, energy and the atmosphere, then Units 12–19 for weathering, tectonics and landforms.
• Optional or selective: Unit 2 (astronomy) can be skimmed. Units 8–11 suit courses with a geology or laboratory component; others can take Unit 9 on the rock cycle and skim the rest.
• Use the objectives as a checklist. After each unit, answer each stated objective briefly from memory, then compare with the unit summary.
• Watch the linked videos in Units 8 and 12–15 and 18; several show the author explaining processes in the field.
• Add what is missing. Pair Unit 7 with a climate-regions chapter and add a biogeography and soils source, for example the corresponding chapters of Strahler or Geosystems. Make a personal glossary, since the book has none.

Edition and Sources

This guide is based on reading Version 2 (2023) of the book, downloaded as a PDF from the folder linked on College of the Canyons' Zero Textbook Cost page (https://drive.google.com/drive/folders/1oTVcpLRpb9YYHCxMp_UdzFHOxTL-Pj2G); it draws on the front matter and preface, the table of contents, and every unit's goals and objectives, section headings and summary, with selected sections of Units 1, 5, 6, 7, 17 and 19 read in full, and on the three reviews of the Open Textbook Library record for Version 1.