Subsidence

Question 1

Venice is ____ because it is built on _____, ______ sediment

Answer 1

• sinking

- loose, muddy

Question 2

subsidence is slow or rapid, nearly _____ downward movement of _______

Answer 2

• vertical

- Earth’s surface

Question 3

karst is ______ resulting from ______ of limestone, dolostone, marble, gypsum or rock salt

Answer 3

• landscape

- dissolution

Question 4

soil expansion and contraction is due to changes in _________ of soil as well as _____ and ______

Answer 4

• water content
• freezing
• thawing

Question 5

sinkholes in large numbers form a ______

Answer 5

karst plain

Question 6

karst is a common type of landscape associated with ______

Answer 6

subsidence

Question 7

rocks are dissolved by _____ or ______

Answer 7

• surface

- groundwater

Question 8

dissolution produces ____ which join to form caves and ______

Answer 8

• voids

- sinkholes

Question 9

sinkholes can range from ________ in diameter

Answer 9

1 to 100’s of metres

Question 10

solution sinkholes are ____ formed by solution of ____ _____

Answer 10

• pits

- buried bedrock

Question 11

a collapse sinkhole is ______of ____ or near-_____ rock or sediment

Answer 11

• collapse

- surface

Question 12

sinkholes damage:

Answer 12

• highways
• homes
• sewage facilities

Question 13

cave systems are formed when _____ produces a series of ______

Answer 13

• dissolution

- caves

Question 14

groundwater seepage in cave systems causes:

Answer 14

• flowstone
• stalagmites
• stalactites

Question 15

tower karst is created in highly ______ karst regions

Answer 15

eroded

Question 16

disappearing streams occur when streams disappear into ____ ____

Answer 16

cave openings

Question 17

springs occur where ______ naturally flows onto the ______

Answer 17

• groundwater

- surface

Question 18

caves create direct access between ____ and ______

Answer 18

• surface

- groundwater

Question 19

permafrost is when _____ or _____ has been frozen for at least ____

Answer 19

• soil
• sediment
• 2 years

Question 20

the active layer in permafrost _____ in winter and _____ in summer

Answer 20

• refreezes

- thaws

Question 21

when permafrost thaws, it can create ____ _____

Answer 21

land subsidence

Question 22

extensive thawing of permafrost creates _____ soil called ______

Answer 22

• uneven

- thermokarst

Question 23

permafrost is continuous if its mean annual temperature is less than _____

Answer 23

-5 degrees C

Question 24

sediment piping is ______ moving through _______

Answer 24

• groundwater

- loose sediment

Question 25

removing groundwater through pumping can result in ______ of land due to ______ of pore space that was occupied by _____ and supported by the _____ _____

Answer 25

• subsidence
• collapse
• water
• water pressure

Question 26

fine sediment ______ when pore water is removed, and is common on ____ ______

Answer 26

• collapses

- river deltas

Question 27

organic sediments are when _____ soils contain large amounts of _____ matter and ____

Answer 27

• wetland
• organic
• water

Question 28

expansive soils commonly have _____ and _____ during wet periods and _____ during dry periods

Answer 28

• clay
• expand
• shrink

Question 29

human causes of subsidence:

Answer 29

• underground mining
• water withdrawal
• melting permafrost
• restricting deltaic sedimentation by constructing dams

Question 30

how to minimize subsidence hazard:

Answer 30

• restrict fluid withdrawal
• regulate mining
• prevent damage from thawing permafrost
• controlled flooding to rebuild marshes