Geol 201 Quiz 4 Questions

From an engineering perspective, the most important component of a soil is

the clay content

The Leaning Tower of Pisa is leaning because of

consolidation of underlying clay layers

Water moves into soil particles in an expansive soil because of

attraction by negatively charged surfaces of sheets in clay minerals

This picture illustrates

a diffuse double layer at the surface of a clay-colloid particle

What caused land subsidence of 30 ft between 1925 and 1977 in the San Joaquin Valley, California?

Excessive pumpage of groundwater for irrigation

Which of the following is a form of mechanical weathering?

Frost action, exfoliation, salt weathering, and biogenic processes.

Differential weathering of igneous rocks is due to

different susceptibility of mafic and felsic rocks to chemical weathering

The type of soil that forms at a given locality depends on

climate, parent material, time, relief, and bio activity.

A cohesive soil

contains silt and clay and is fine grained

The Atterberg limits are defined using values of

water content

The difference between the height water will rise in a well at two different points divided by the distance between these points is called the

hydraulic gradient

Equipotential lines on a flow net indicate

equal hydraulic head

The elevation of the water table in an unconfined aquifer is

equal to hydraulic head

The combination of water and carbon dioxide forms

carbonic acid

Weathering of feldspars by hydrolysis produces

clay minerals

The chemical reaction 4FeSiO3 + O2 + H2O → 4FeO(OH) + 4SiO2 describes

oxidation of silicate mineral pyroxene into the iron-oxide-hydroxide mineral limonite

The zone of maximum leaching (eluviation) in a soil is called an

E horizon

The soil classified as GP on the Unified Classification System is

poorly graded gravel

Soils in which clay particles have edge-to-face contact (like a house-of-cards) are said to have a ___ fabric

flocculated

The level to which water rises in a well that penetrates a confined aquifer is called the

potentiometric surface

According to the elastic-rebound theory

deformation of rocks is continuous until rupture and fault movement occur at a critical level, producing a major earthquake

How much larger is the amplitude of ground displacement for a magnitude-7 earthquake compared to a magnitude-5 earthquake?

100 times

The largest ground shaking usually occurs in areas underlain by

soft soil

Seismic-wave attenuation is

decrease in wave amplitude away from the source