S through Z

S THROUGH Z:

• Salt – this is any ionic compound that dissolves in water. Calcium salts and sodium salts are commonly discussed in geology.

• Saltation – this is when sand grains bounce along because of the activities of flowing water or windy conditions.

• Sand – these are tiny particles up to 2 mm in diameter that are made from quartz and resistant to most chemical breakdown techniques.

• Sandstone – this is sedimentary rock that has medium grains within its structure and that consists of cemented sand grains.

• Schist – this is metamorphic rock that has shiny mica in it that is arranged in a foliated way.

• Sea-stack – this is a tall pillar of rock you can see coming up out of the sea and worn into a pillar by the action of waves eroding the rock.

• Sediment – this is any type of material that layers out due to the action of standing water and gravity. This can be anything – sand, organic material, shells, mud, or pebbles. Sediment may or may not become rock.

• Sedimentary rock – are formed on or near the Earth's surface from the compression of ocean sediments or other processes.

• Shale – this is a rock that was compressed to make dark-colored, grayish sedimentary rock. Expect to see fine, microscopic grains.

• Sill – this is an intrusion or influx of igneous rock that has seeped in along the planes of other rock layers.

• Slate – this is metamorphic rock made through compression of mudstone.

• Soil creep – this is mass movement that happens gradually due to gravity on steeper mountains or hillsides.

• Strata – these are any layers you see within rock itself, usually made by sediment of some kind.

• Strike-slip fault – this is a fault that involves a section of rock that moves past another in a horizontal fashion.

• Suspension load – this is a load of clay or other fine particles that get carried through the action of water and wind; they settle out eventually when the conditions are less fierce.

• Syncline – this is when a rock has bulged in a downward fashion or appears sunken in the middle.

• Tectonic forces – these are those forces that either crush or stretch the surface of the earth. This leads to faults, mountain building, and folding or shearing of the earth.

• Tectonic plates – these are stiff or rigid sections of the earth's crust that move independently from other plates.

• Texture – rock texture is described completely according to the size of the grains in the rock itself and the rock's shape due to the presence or absence of weathering and other factors.

• Thrust fault – this is often called a reverse fault because large sections of rock have slid up and over another section of rock.

• Unconformity – this involves the boundary layer between two separate rock sections that have cut across one another, leading to an apparent gap in geological time.

• Uplift – this is when a section of the earth's crust is squashed by tectonic plate activity or perhaps by ice sheets that have melted in varying ways.

• Vent – this is often seen in volcanic craters and is where gases and magma erupt to allow contents beneath it to escape.

• Vesicles – these are bubbles of rock that are made when gases beneath the earth are emitted from volcanoes. The lava cools and freezes the lava into vesicles.

• Volcanic ash and gases – these are the "stuff" emitted from a volcano. Gases are often made from carbon dioxide, water vapor, and sulfur gases.