Soil Mechanics

Rock

a natural aggregate of minerals that are connected by strong bonding or attractive forces

Soil

defined as the unconsolidated sediments and deposits of solid particles that have resulted from the disintegration of rock

Voids

exist between particles; filled with a liquid (usually water) or a gas (usually air)

Soil Mass

consists of an accumulation of individual particles that are bonded together by mechanical or attractive means

Igneous rock

resulted from the cooling and hardening of molten rock called magma, which originated deep within the earth

Extrusive or Volcanic Rock Type

The molten materials (lava) that cooled rapidly at or near the Earth’s surface

Basalts, Rhyolites, and Andesites

examples of extrusive igneous rocks

Intrusive or Plutonic Types

molten rock trapped deep below the surface of the earth (magma) cooled slowly

Granites, Syenites, Diorites, and Gabbros.

examples of intrusive igneous rocks

Predominantly Sandy or Gravelly Soil with Little Clay

rock whose chief mineral is quartz or orthoclase (potassium feldspar), minerals with high silica content decompose to what type of soil

Acidic Rocks

rocks such as granites, syenites, and rhyolites with high silica content are classified as

Basic Rocks

rocks whose minerals contain iron, magnesium, calcium, or sodium, but little silica, such as the gabbros, diabases, and basalts are classified as

Fine-textured Silt and Clay Soils

basic rocks decompose to what type of soil

Light-colored

acidic rocks are usually what shade of color

Very Dark

basic rocks are usually what shade of color

Clays

are not small fragments of the original minerals that existed in the parent rock

Sedimentary Rocks

formed from accumulated deposits of soil particles or remains of certain organisms that have become hardened by pressure or cemented by minerals

limestones and dolostone (dolomites), shale, sandstone, conglomerate, and breccia

examples of sedimentary-type rocks

Limestones, Shales, and Sandstones

accumulated sediments in shallow seas eventually become

Shale

a sedimentary rock predominantly formed from deposited clay and silt particles

Sandstone

predominantly quartz cemented together with mostly silica, but also calcium carbonate, or iron compounds

Limestone

predominantly crystalline calcium carbonate (calcite) formed under water.

Karst or Karstic terrain

Limestone, and limestone-dolomite, formations may be referenced as

Sinkhole

rock cap for a cavity located near the surface of the limestone formation deteriorates, a typical result is that the overlying earth material collapses into the void

Dolostone

is a variety of limestone, but harder and more durable

Marl and Chalk

are softer forms of limestone

Metamorphic Rock

results when any type of existing rock is subject to metamorphism, the changes brought about by combinations of heat, pressure, and plastic flow so that the original rock structure and mineral composition are changed

Plastic Flow

refers to slow viscous movement and rearrangement within the rock mass as it changes and adjusts to the pressures created by external forces

Marble

under a metamorphic case, limestone can changed to what

Quartzite

under a metamorphic case, sandstone can change to what

Slate or Phyllite

under a metamorphic case, shale can change to what

Schist

under a metamorphic case in higher levels, shale can change to what

Gneiss

a foliated rock with distinctive banding that results from the metamorphosis of sedimentary rock or basalt or granite

Silt–sand Mixtures with Mica

gneiss and schist decompose to what type of soil

Clayey

slates and phyllites decompose to what type of soil

Sandy and Gravelly

quartzite decompose to what type of soil

Residual Soil 

formations are created from the weathering of rock or the accumulation of organic materials where the material remains at the location of origin

Transported Soils

materials that have been moved from the place of origin

Residual Formations

soil formations that are more apt to be found in humid and tropic regions of the planet

Transported Soils

soil formations that are more prevalent for the temperate and cold climatic regions.

Size

transported soils are usually segregated according to

Gravity

generally capable of transporting aggregate particles only limited distances, such as down a hill or mountain slope, with the result that little change in the soil material is brought about by the transportation procedure.

Wind 

move small particles by rolling or carrying them. Soils carried by wind and subsequently deposited

Aeolian deposits

wind-transported soils are usually called

Dunes

are typically characterized by low hill and ridge formations from the accumulations of wind-deposited sands

Clay

has sufficient bonding or cohesion to withstand the eroding effects of wind

Loess

Deposits of wind-blown silts laid down in a loose condition that has been retained because of particle-bonding or cementing minerals is classified as

The Great Ice Age

the most recent geological period of glaciation is referred to as

Glacial Drift

quantities of soil have been moved and deposited by or because of glacial action

Glacial Till

glacial deposits are a heterogeneous mixture of all soil sizes and are termed

Ground Moraine or Till plain

the land form or topographic surface resulting after a glacier receded

Terminal Moraines

the hills and ridges of till that formed at the front of the glacier and marked its farthest advance

Recessional Moraines

hills or ridges that represent deposits along the front of a glacier where it made temporary stops during the recession process

Lateral Morraine

debris dropped along the side of a glacier as it moved through a valley

Drumlins

long low hills of till that extend in the direction of the glacial movement

Eskers

soils deposited by the surface and subsurface glacial rivers, to remain in the form of long winding ridges

Kettle Holes

apparently formed when great blocks of ice remained after a glacier receded and became buried by the glacial soil

River Deposits

flowing bodies of water are capable of moving considerable volumes of soil by carrying the particles in suspension or by rolling, sliding, and skipping them along the river bottom

Square of the Velocity

The largest-diameter particle that can be carried in suspension is related to what of the flowing water

Coarser Particles

particles that are being carried in suspension are dropped when a decrease in the water velocity occurs, as when the river deepens, widens, or changes direction

Finer Particles

particles that remain in suspension to be deposited in quieter waters.

Alluvial Deposits

all soils carried and deposited by rivers are classified as

Glaciofluvial Deposits or Stratified Drift

glacial soils carried by rivers created from melting glacial water

Outwash Plains

overlapping deltas of coarse soils spread over broad areas created land forms classified as

Alluvial Fans

coarse soil particles dropped out to form submerged spreading triangular-shaped deposits are termed as

Natural Levees

the overflow velocity quickly diminished, and the heavier gravel and sand particles dropped out in the vicinity of the bank, forming low ridges called as

Floodplain Deposits

the broad lowland areas on either side of the river were also flooded over, but the materials dropped in these areas were the finer-grained soils

Meander Bends

the velocity of the flowing water can vary considerably between the inside and outside edges of the curve. These natural curves are called

Oxbow Lake

when a river shortcuts a large bend when eroding a new route, the old channel left behind is cut off from new flow, and the trapped water forms an

Lacustrine Deposits

soil formations remaining at the locations of former lake areas are termed

Laminated

When layers are less than 1 cm in thickness, the sediments are described as

Varves

Laminations that have been deposited over a one-year period

Marine Clays

The silt and clay then settled out of suspension at about the same rate, creating deposits of

Beach Deposits

are predominantly sand materials and are constantly being changed by the erosive and redistributing effects of currents and wave action

Bars

Long ridges of sand that form slightly offshore are termed

Longshore Bars

when the formation of the bars that develops includes two or more submerged ridges

Offshore Bar or Island Bar

when a small exposed ridge forms offshore from a gently sloping beach, the formation is termed 

Barrier Bar

a deposit that almost completely blocks

the entrance to a bay

Spit

a sand or sand–gravel accumulation that is connected to the shore and extends into open water like a finger

Swamps and Marshes

develop in stagnated areas where

limited depths of water accumulate, or where periodic inundation and drying occur because of fluctuations in the groundwater level, and vegetation therefore has the chance to grow

Muck

geologically older than peat, is almost fully decomposed vegetation, and is relatively dense

Peat

includes partially decomposed vegetation and is normally spongy and relatively light

Sanitary/ Solid waste/ landfill

the technique of using burial methods for disposing of solid waste resulting from human activities

Leachate

resulting polluted liquid from surface and subsurface water passing through the buried waste can place into the solution undesirable particle matter, bacteria, and chemicals

Residual soils (or sedentary soils)

have principally formed from the weathering of rock or accumulation of organic material, and remain at the location of their origin

Mechanical weathering

to physical disintegration resulting from the effects of wind, rain, running water, ice and frost wedging, and tectonic forces.

Chemical and solution weathering

rock decomposition due to chemical reactions in the rock materials that result from exposure to the atmosphere, temperature changes, water, water-based solutions, or other materials.

Saprolite

refers to material that is essentially soil, but which includes physical features representative of the parent rock

Lateritic Soils

soils with an absence of silica and alkalines, but enriched with iron and aluminum compounds

Plate Tectonics 

deals with the development, formation, and changes occurring to the earth’s land and ocean areas on a long-term, large-scale basis

Lithosphere

outer zone, ranging from about 70 to 150 km thick consisting of dense and hard brittle rock materials

Asthenosphere

underlying the lithosphere that has a 200- to 250-km-thick zone of dense, semi-solid, or plastic rock material 

Rift

develops where plates of lithosphere are moving apart, creating the condition where molten rock from the asthenosphere rises to create new lithosphere and crust; volcanism is involved

Sea-floor Spreading

plate divergence and the creation of new lithosphere in ocean ridge zones

Trenches

boundaries where subduction occurs

Diverging

plates of lithosphere are moving apart

Converging

plates of lithosphere are towards each other

Transform Faults

boundaries where plate edges slide past each other are classified as

Earthquakes

relate to the quick release of strains (deformations) that build up within

Gravel

soil type with upper size limit that varies from 80 mm up to about 200 mm