Soil Formation and Types of Soil

Vocabulary practice cards covering the classification and characteristics of various rocks and soil types discussed in the lecture.

Igneous Rocks

Rocks formed by the solidification of molten magma ejected from deep within earth’s mantle.

Sedimentary Rocks

Rocks formed by the accumulation or deposition of mineral or organic particles at the surface of the Earth, followed by cementation.

Metamorphic Rocks

Rocks formed when existing rock is transformed physically or chemically at elevated temperature.

Quartz – Syenite

A medium-to-coarse-grained rock that is pinkish-grey, reddish-tan, or buff grey in color.

Basalt

A fine-grained rock, dark grey to black in color, which can weather to reddish-brown or dark green.

Rhyolite

An aphanitic rock with colors ranging from light pink, buff, and cream to light reddish tan.

Basaltic Glass

A pitch black, dark brown, or greenish-black rock with a glassy texture and resinous luster that features sharp conchoidal fracturing.

Pumice

A light grey, off-white, cream, or pale tan rock characterized by a sponge-like structure.

Phyllite

A rock featuring phyllitic foliation, characteristically wrinkled or wavy surfaces, and a pronounced silky, satiny sheen; colors include silvery-grey and iridescent pearl grey.

Serpentinite

A rock with a waxy, smooth, or greasy feel and a granoblastic texture; occurs in mottled green, dark olive-green, or blackish-green.

Eclogite

A medium-to-coarse-grained rock referred to as “Christmas rock” due to its bright green matrix studded with reddish-pink crystals.

Glaucophane Schist

A well-foliated, fine-to-medium-grained rock with a distinctive lavender-blue, dark blue-grey, or indigo color.

Carbonaceous Slate

A very fine-grained, dark charcoal grey or jet black rock that leaves a dark streak.

Breccia

A clastic, coarse-grained rock with sharp, angular, jagged rock fragments set in a fine matrix.

Congolomerate

A clastic, coarse-grained, clast-supported rock characterized by rounded to well-rounded pebbles.

Chalk

An extremely fine-grained, soft, and porous rock that is bright pure white or off-white and leaves white powder when rubbed.

Arenite

A clastic grain-supported sandstone with minimal mud matrix, appearing pure white, cream, or light grey.

Alluvial Soils

A specific category of transported soils moved by water.

Lacustrine Soils

A category of transported soils associated with lake environments.

Aeolian Soils

A category of transported soils moved by wind.

GW: Well-Graded Gravel

Very coarse, clean, interlocking, angular to sub-rounded rock fragments with a wide, continuous distribution of sizes; non-plastic with high interparticle friction.

CH: Fat Clay

Extremely slick, greasy, highly plastic, and intensely sticky when wet; forms rock-hard clods and is prone to severe shrinking and cracking upon drying.

Pt: Peat

Highly fibrous, spongy, lightweight, and intensely compressible soil composed of partially decomposed plant fibers and roots.

Sandy Loam

Moderately gritty soil that forms a pliable cast when wet and can form a weak ribbon up to $2.5\,cm$ long before breaking.

Silt

Extremely smooth, soft, and flour-like when dry; slippery or buttery when wet with no gritty feel.

Silty Clay

Extremely smooth, slick, plastic, and sticky when wet; forms long, strong, shiny ribbons $> 5\,cm$ with zero gritty feeling.