McCarthy - Geotechnical Engineering Chapter 1

Rock

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

Soil

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

Igneous Rock

These are rocks that resulted from cooling and hardening of rocks called magma.

Lava

Molten magma that escaped to and near the surface of the earth through volcanoes and fissures in the Earth’s Crust/

Extrusive / Volcanic Rock

Molten materials that cooled rapidly at or near the earth’s surface

Intrusive / Plutonic Rock

Molten rock trapped deep below the surface of the earth cooled slowly.

Clay

the result of primary rock minerals decomposing to form secondary minerals.

Sedimentary Rocks

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

Shales

predominantly formed from deposited clay and silt particles

Hardness

generally due to external pressures and the particle bonds that resulted.

Weathering

breaks down shale to fragments of varying sizes.

Sandstone

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

Conglomerate

Cemented sand and gravel

Breccia

Cemented angular rock fragments

Limestone

predominantly crystalline calcium carbonate formed under water

Metamorphic Rock

These are rocks that resulted when any type of existing rock is subjected to metamorphism, changes brought about by combinations of heat, pressure, and plastic flow.

Plastic Flow

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

Gneiss

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

Residual Soil

These soil are created from the weather of rock or the accumulation of organic materials where the material remains at the location of origin.

Transported Soil

Those materials that have been moved from the place of origin; May have resulted from the effects of gravity, wind, water, glaciers, or human activity.

Residual Soil

more apt to be found in humid and tropic regions of the planet

Transported Soils

more prevalent for the temperate and cold climatic regions.

Gravity

Capable of transporting aggregate particles only limited distances, such as down a hill or mountain slope.

Colluvium Deposits

Deposits formed by gravity.

Wind

can move small particles by rolling or carrying them.

Aeolian Deposits

Soils carried by wind and subsequently deposited are designated.

Dunes

Accumulations of wind-deposited sands. These are typically characterized by low hill and ridge formations. Generally occurring in sand desert areas and on the down-wind side of bodies of water.

Loess

Deposits of wind-blown silts laid down in a loose condition

Glacial Drift

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

Ground Moraine / Till Plain

land form or topographic surface resulting after a glacier receded.

Terminal Moraines

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 glacier where it made temporary stops during the recession process.

Lateral Moraine

Debris dropped along the side of a glacier

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

Kames

soil deposits of somewhat similar to eskers; they are the remains of material dropped along the boundaries of a glacier and a valley wall.

Kettle Holes

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.

Alluvial Deposits

All soils carried and deposited by rivers.

Glaciofluvial deposits

Glacial soils carried by rivers created from melting glacial waters.

Outwash plains

Overlapping deltas of coarse soils spread over broad areas created land forms.

Alluvial Fans

coarse soil particles drop out to form submerged spreading triangular-shaped deposits.

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.

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

Where rivers bend or curve to change direction, the velocity of the flowing water can vary considerably between the inside and outside edges of the curve.

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, then the trapped water forms.

Lake Deltas

The coarsest soil particles carried by rivers feeding into the lake would fall out of suspension quickly after entering the lake area because of the sharp decrease in velocity.

Lacustrine Deposits

Soil formations remaining at the location of former lake areas.

Laminated

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

Laminated Clay

Deposits of such find sand-silt and clay layering

Varves

Laminations that have been deposited over a one-year period.

Marine Clays.

Clay particles flocculated in the presence of the saltwater, then the silt and clay settled out of suspension at about the same rate, creating deposits of ____.

Beach deposits

These 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.

Offshore Bar or Island Bar

A small exposed ridge forms offshore from a gently sloping beach.

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.

Swamp and Marsh Deposits

They develop in stagnated areas where limited depths of water accumulate, or where periodic inundation and drying occur because of fluctuations in the ground water level, and vegetation therefore has the chance to grow.

Muck or peat

Accumulations of decomposed or partially decomposed aquatic plants in swamp or marsh areas.

Sanitary Landfills

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

Mechanical Weather

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 results from exposure to the atmosphere, temperature changes, water and water-based solutions.

Thickness of residual soil

affected by the rate of rock weathering and the presence or absence of erosive forces to move the accumulation of particles.

Saprolite

material that is essentially soil but which includes physical features representative of the parent rock.

Lithosphere

Outer zone, ranging from about 70 to 150 km thick that consists of dense and hard brittle rock materials.

Asthenosphere

a 200 to 250 km thick zone of dense, semi-solid or plastic rock material.

Diverging

plates of lithosphere that are moving apart

Convering

plates of lithosphere that are moving toward each other or sliding past each other/

Rift

developed where plates of lithosphere are moving apart, creating the condition where molten rock from the asthenosphere rises to create a new lithosphere and crust.

Sea-floor spreading

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

Ridges

Plate boundaries where plates are spreading apart.

Trenches

The subducted section of lithosphere passes into or through the asthenosphere, where it is absorbed. Boundaries where subduction occurs are identified as ___.

Transform Faults

boundaries where plate edges slide past each other. These occur at plate boundaries originally created by divergence or convergence.