Soils test 1

engineering geology

the branch that deals with the application of geologic principles to engineering works

igneous rocks

magma cools as it moves upward toward the ground surface

two primary types of igneous rocks

intrusive (plutonic) rocks and extrusive (volcanic) rocks

intrusive (plutonic) rocks:

below the ground surface; slow cooling process; coarse grained

extrusive (volcanic) rocks:

at the ground surface; rapid cooling; fined grained

unweathered igneous rocks

generally have excellent engineering properties and are good materials to build on. however, fractures in rocks form planes of weakness along which rock can slide

examples of intrusive rocks:

granite, diorite, and gabbro

examples of extrusive rocks:

rhyolite, andesite, and basalt

sedimentary rocks:

soil deposits can be transformed into rock through hardening process called induration or lithification forming __

two primary types of sedimentary rocks:

clastic and carbonated rocks

clastic rocks:

pressure from overlaying strata and cementation through precipitation; layered/ stratified

carbonated rocks:

organic materials origin; generally consisting of CaCO₃

clastic rocks examples:

sandstone, shale, conglomerate

carbonated rocks examples:

limestone, chalk, dolomite

dissolved by long exposure to water

Because of their organic origin carbonated rocks can be ______ and may create underground caverns (karst topo). when the soil above caves into the caverns, it creates a sinkhole

metamorphic rocks:

both igneous and sedimentary rocks can be subjected to intense heat and pressure, thus forming the __

foliation

during metamorphic process, particular mineral grains are oriented along directions, which is called _

two types of metamorphic rocks:

foliated and nonfloated rocks

examples of foliated rocks:

slate, schist, and gneiss

examples of nonfoliated rocks

quartzite and marble

strike:

a compass direction of the intersection of the geologic surface and the horizontal ( N30^oE )

dip:

an angle between the geologic surface and the horizontal ( 20^oSE )

attitude

strike and dip ( N30^oE; 20^oSE )

formation of soils:

residual soils and transported soils

physical weathering:

disintegration of rocks into smaller particles through physical or mechanical process.

• the erosive active of water, ice, and wind

• opening of cracks as a result of unloading

• loosening through the growth of plant roots

• thermal expansion and contraction/thaw actions

• landslides and rockfalls

chemical weathering:

disintegration of rocks through chemical reactions between the minerals in the rock, water, and oxygen

• solution, hydration, carbonation, oxidation

residual soils:

soils that remain in place because of faster weathering process than the transporting process; common in tropical regions.

• decomposed granite; saprolite; laterite

transported soils:

soils that formed by the deposition of sediments that have been transported from their places of origin by various agents

• glacial soils

• alluvial (fluvial) soils

• lacustrine and marine soils

• aeolian soils

• colluvial soils