The lecture begins by revisiting folding, where rock layers buckle under compression from plate movements, citing Pennsylvania's ridge and valley region as an example. It then introduces faulting, where rock breaks or fractures, leading to escarpments, rift valleys (like the East African Rift Valley), and joints, which are simple cracks.

Earthquakes are discussed as movements along faults, caused by the shifting of continental and oceanic plates. The Northwest's Wafuca plate subducting under the North American plate is highlighted as a local example. The magnitude of an earthquake correlates with the extent of plate movement, and while most are imperceptible, catastrophic ones like the 1976 China earthquake and the 2011 Japan earthquake are noted. Tsunamis, often caused by earthquakes, volcanic eruptions, or underwater landslides, are explained as fast-traveling, low-height waves in deep water that grow significantly higher and slower as they approach shallower shores, carrying destructive debris.

Volcanism, another tectonic force, predominantly occurs at plate intersections or hotspots like Hawaii. Hotspots are breaks in the Earth's crust where molten material (magma) rises, forming volcanoes. Hawaii's islands are explained as forming as the Pacific plate moves over a stationary hotspot, with older islands to the northwest and newer ones forming to the southeast. The lecture differentiates between explosive strata (composite) volcanoes, characterized by steep sides and alternating layers of lava and ash, and non-explosive shield volcanoes (like those in Hawaii) with gently sloping sides and effusive lava flows. Examples include Mount St. Helens as a strata volcano and Kilauea as a shield volcano.

Gradational processes, responsible for reducing the Earth's surface, are introduced, starting with weathering—the breakdown of rocks and minerals by atmospheric factors. This includes mechanical weathering (e.g., frost action, root action) and chemical weathering (e.g., oxidation, carbonation). Weathering creates soil, which is then moved by gravity and erosional agents in a process called mass wasting, encompassing avalanches, landslides, mudflows, and soil creep. Accumulations of rock particles at the base of mountains due to mass wasting are known as talus.

Running water is presented as a highly effective erosional agent, with its ability to erode depending on rainfall, slope, rock type, and vegetation. Materials transported by a stream are called its 'load.' When a stream's speed decreases, it deposits its load, forming deltas (e.g., Mississippi River Delta) and floodplains (like the Missouri River Floodplain of 2018). The lecture contrasts stream landscapes in humid areas (waterfalls, V-shaped channels, rapids, meandering streams, oxbow lakes, natural levees, rounded landforms) with arid areas (temporary lakes, alluvial fans, arroyos, buttes, and mesas), where lack of vegetation enhances erosion. An oxbow lake, often formed during floods when a river cuts a new, straighter path, is described in detail.

Groundwater, precipitation that sinks into the earth, is discussed. An aquifer is an underground water-bearing structure, with the water table marking its upper level. Land dipping below the water table forms ponds, lakes, and streams. Groundwater, propelled by gravity, moves slowly and can dissolve soluble materials, especially limestone when combined with carbon dioxide. This chemical process leads to the formation of underground caverns, stalagmites, stalactites, and sinkholes—features characteristic of Karst topography, seen in areas like Mammoth Cave in Kentucky and East Central Florida.

Glaciers, large masses of slow-moving land ice, are significant agents of erosion and deposition. They form when snowfall exceeds melt and evaporation, compacting into ice that slowly flows, essentially like 'toothpaste.' Two types are identified: continental glaciers (Antarctica, Greenland, Baffin Island) and mountain glaciers (Mount Rainier). Glaciers break up and transport underlying rock, scouring the land and leaving scratches that reveal their past presence. As they melt, they deposit debris, creating various landforms.

Glacial landforms include U-shaped glacial troughs, fjords (U-shaped valleys filled by the sea), circs (amphitheater-like basins), arêtes (steep ridges between glaciers), and horns (sharp peaks formed by multiple arêtes, like the Matterhorn). Depositional glacial features include moraines (ridges of deposited material, showing glacial extent or retreat), eskers, drumlins (small hills), and outwash plains. Kettle lakes and kames are also described as depressions or mounds of sediment left after glacier retreat. The lecture then transitions to coastal landforms, explaining how ocean waves carry and deposit sand (forming beaches) and erode landforms, carrying away material (backwash) to form cliffs, spits, and sandbars. Longshore currents, running parallel to the coastline, transport sand to create spits (e.g., Port Angeles). Offshore sandbars, extending to form lagoons or salt marshes, are exemplified by the Outer Banks of North Carolina. Coral reefs are introduced as structures formed by coral organisms in shallow tropical waters, and atolls (common in the South Pacific) are explained as reefs built on submerged volcanoes.

Wind is highlighted as a powerful erosional and depositional agent in dry climates where limited vegetation exposes particles to wind. The abrasive action of sand and dust particles can sculpt features (like in gravel deserts such as the Sahara or Gobi) and create sand dunes (e.g., Oregon sand dunes) that move across deserts. Wind also produces loess, which are deposits of windblown silt. These form rich soils and are among the most agriculturally productive lands globally, notably found in the mid-latitude westerly wind belts of the United States (Great Plains, Midwest) and northern China.

The lecture concludes by defining landform regions as large sections of the Earth's surface with homogeneous landform types, including mountains, plains, and plateaus. It marks the end of the physical geography section of the course, transitioning to human geography for the following week.