Exposed ground is continually altered by weathering, erosion, gravity, water, wind, and ice. These articles investigate soil development, sediment transport, landslides, and the mechanisms that wear down or rearrange surface materials.
The intense red and yellow colors of many tropical soils can suggest richness, but color alone says little about fertility. In old, humid landscapes, prolonged chemical weathering can remove much of what once made the parent rock chemically complex. Soluble elements are carried away in drainage...
A vertical cut through soil is a record of processes rather than a simple stack of dirt. Colors change, roots thin out, textures shift, and rock fragments become more common with depth. Soil scientists organize these changes into horizons: layers that formed through additions, losses, movement, and...
Lichless: a crust of gray, yellow, orange, or green spread across a surface that may have endured for thousands of years. At the contact between lichen and rock, however, a slow sequence of physical and chemical changes is underway. Lichens are not simply resting on stone. Many species alter the...
Salt can break stone without striking it, dissolving it outright, or freezing inside it. The process begins when saline water enters a porous rock. If evaporation or a chemical change makes that solution supersaturated, crystals form within the pore network. Growth in a confined space presses...
Some bare rock hills rise as smooth, rounded masses crossed by fractures that follow the shape of the surface. Along those fractures, slabs can separate like nested shells. This pattern is exfoliation: the development and detachment of broad sheets from an exposed rock mass. It is especially...
A crack in a mountain wall may hold only a thin film of water, yet repeated freezing can turn that opening into a route for failure. This mechanical breakdown is commonly called frost wedging, freeze-thaw weathering, or frost cracking. It helps loosen blocks on high peaks, cold cliffs, and...
Feldspar looks durable in a hand specimen, yet it becomes chemically vulnerable once erosion exposes it near Earth’s surface. The name covers a family of aluminum-rich silicate minerals containing potassium, sodium, or calcium. Together, feldspars make up more of the continental crust than any other...