surface processes

Question 1

types

Answer 1

sea
rivers
groundwater
weathering
geohazards and landslides
earthquakes
two cause hypotheses of earthquakes

Question 2

sea

Answer 2

• wave erosiona and brushing on rocks wears at lower strata creating cliffs.
• conglomerates usually give away to these waves
• waves are produced by frictional drag of wind
• in HK pearl river, seawater goes from E-W

Question 3

rivers

Answer 3

-common chinese rivers: Yangzte, xiao-jiang catchment basin

Question 4

groundwater

Answer 4

results from permeable rock giving water from pressure of some kind

Question 5

pervious

Answer 5

permeable

Question 6

unconfined aquifers

Answer 6

• groundwater only partially fills aquifer
• levels follow contour of land and bodied water
• can be contaminated from surface activity

Question 7

confined aquifers

Answer 7

• aka artesian aquifers
• sandwiched between 2 confining beds creating pressure
• water level in well when drilled is the pressure surface

Question 8

weathering

Answer 8

• mechanical disintegration

- chemical decomposition

Question 9

mechanical weathering or disintegration

Answer 9

• caused by physical processes such as frost, permeating water, and temp/stress changes
• results in opening/new discontinuities, rock/mineral grain fracture
• another common in hk, Tree root expansion/growth

Question 10

chemical weathering or decomposition

Answer 10

• chem rxtions change rocks into new rocks
• hydration, oxidation, ion exchange/solution
• silicate minerals>clay minerals
• quartz survives
• carbonate rocks

Question 11

grades of chem decomposition

Answer 11

• slightly Decomposed: stained near joints
• moderately “: easily broken by geo hammer and is completely stained
• highly “:broken by hand
• completely “: is soil but still has original rock texture
• residual soil: is soil with no rock texture

Question 12

Mechanical strength of weathered granite

Answer 12

-grades 1-4, 1 is unweathered

Question 13

mass weathering

Answer 13

• largely controlled by joint characteristics

- plutonic rocks is of importance to geo eng

Question 14

Mechanical strength of tuff

Answer 14

• grades 1-4, 1 and 2 are extremely strong

- stronger and more abrasive than granite

Question 15

corestone

Answer 15

A rounded or broadly rectangular joint block of granite formed as a result of subsurface.

Question 16

weathering of carbonate rocks

Answer 16

• calcite dissolves with h2o

- mechanical weathering can happen too

Question 17

classification of rock mass weathering

Answer 17

-PW90/100: rock occupies 90 to 100% and soil occupies 10 to 0%of exposed area, similar numbering for rest of situations

Question 18

products of rock weathering

Answer 18

• original minerals form in-situ soils
• new clay minerals form “
• solutions flow away from chem

Question 19

geohazards

Answer 19

• events caused by geo features and the processes that make them
  ex: sinkhole in Guatemala, ground caving (subsidence) in Venice,
• landslides are biggest concern in HK

Question 20

Earthquakes

Answer 20

• releases large amount of energy in short time
• generates seismic waves in crust
• includes focal depth, focus (point of initial rupture, aka hypocenter), epicenter (point on surface above focus)
• mag>8 on richter scale is usually catastrophic

Question 21

Seismic waves

Answer 21

• primary wave (P-wave): compression/dilation wave (slinky)
• secondary wave (s-wave), like a string
• love wave: particles are bunched at peak
• Rayleigh Wave: particles are bunched at trough

Question 22

seismograph

Answer 22

• records earthquakes

- richter scale: M_r=log(A) where the A is the averaged 2 max amplitudes given by wood-anderson type seismograph

Question 23

Two cause Hypothesis of Earthquakes

Answer 23

• elastic rebounding: earthquake energy comes from elastic stress-strain energy in rocks; ex) san andreas fault California
• reids’s theory: fence example
• Deep-Fault-natural gas: Earthquake energy= volumetric Expansion energy of nat gas: ex) wenchuan , lengmen shan, sichuan province