Feature Mapping

Question 1

what is feature mapping

Answer 1

set a techniques used to represent various features of the landscape on plain view (map)

Question 2

why use feature mapping

Answer 2

help map positions of geological boundaries

Question 3

aspects to identify when doing feature mapping

Answer 3

-bedrock at surface
-lineaments
-breaks in slope
-sinkholes and spring lines
-soil and vegetation
-manmade features

Question 4

what are bedrock

Answer 4

-hard, solid rock beneath surface materials such as soil and gravel

• also underlies sand and other sediments on ocean floor

-bedrock is consolidated rock, solid and tightly bound

-overlying material is often unconsolidated rock, made up of loose particles.

Question 5

what are outcrops

Answer 5

-exposed bedrocks

-can be seen on some mountaintops, along rocky coastlines, in stone quarries, and on plateaus

-exposed through natural processes such as erosion or tectonic uplift

Question 6

importance of bedrocks

Answer 6

determining depth and type of bedrock helps describe the natural history of a region, identifying rock formations

Question 7

rockhead

Answer 7

top surface of the bedrock

Question 8

bedrock at surface

Answer 8

used to describe parts of landscape where rockhead is within 1m of land surface

includes areas where bedrock is overlain only by soil and vegetation, and by thin (and typically patchy) superficial deposits that are less than 1m thick, as well as those areas where the bedrock is actually exposed.

areas where bedrock is not at surface usually appear much more ‘rounded’, smoother and less ‘regular’ than areas where bedrock is at surface

Question 9

bedrock at surface in upland terrains

Answer 9

areas where bedrock is at surface:

-dominated by exposures,
-by immature or poorly developed vegetation
-by jagged topography

areas where bedrock is not at surface:

-flat
-highly vegetated
-are typically limited in lateral extent

Question 10

bedrock at surface in lowlands terrains

Answer 10

areas where bedrock is at surface:

-sporadic outcrops
-show ridges, gullies and bumps in the landscape between those outcrops

areas where bedrock is not at surface:

-mounded or irregular lumps and bumps that are without clear trend

flat ground

Question 11

limits to bedrock symbols

Answer 11

dotted black ink line

Question 12

what are lineaments

Answer 12

linear feature in a landscape which are an expression of the underlying geological structures such as a fault

Question 13

lineaments symbol

Answer 13

blue line dot alternations

Question 14

what are breaks in slope

Answer 14

-point in hillside where the gradient (slope angle) changes

-basic idea is that rocks of different competencies will weather differently and produce hills slopes of different angles

-if breaks in slope can be mapped, and they can be related in some way to the underlying rocks, then they can be used to interpret the position of geological boundaries through areas of poorly exposed ground

Question 15

what is a boundary

Answer 15

also known as margin/plate boundary, point where two plates meet

Question 16

breaks in slope for bedrock geology

Answer 16

In most instances, geological boundaries will not coincide with breaks, but they will have some relationship to them

Question 17

breaks in slope for faults in uplands and lowlands

Answer 17

uplands:
lineaments rather than breaks in slope

lowlands:
subdued pattern to the breaks in slope. Clear offsets in breaks, or offsets in patterns of breaks

Question 18

what are springs

Answer 18

where the water table intersects the surface

places where groundwater flows naturally from the aquifer onto the land surface or a body of surface water

Almost all streams and rivers have springs or seepages as their ultimate source, or are fed by them at various points along their courses

Question 19

how is a spring formed and founded

Answer 19

result of an aquifer being filled to the point that the water overflows onto the land surface

or forced to the surface when there is a relative difference in permeability of rocks (flow from more permeable to less permeable)

Question 20

what is an aquifer

Answer 20

body of permeable rock which contains or transmits groundwater

e.g gravel, sandstone, conglomerates, and fractured limestone

Question 21

what is the water table

Answer 21

underground boundary between water-saturated ground and unsaturated ground

underground boundary between the soil surface and the aquifer

Question 22

what is ground water

Answer 22

water found in the aquifer

Question 23

what is a sink hole and how are they formed

Answer 23

depressions in the ground that forms when water dissolves the surface rock

streams may flow and disappear underground

Question 24

where are they typically found

Answer 24

occur only where the underlying geology is limestone

where the underlying geology changes from clastic sedimentary or igneous strata above, to carbonate strata below

Question 25

why interpret soil and vegetation in feature mapping

Answer 25

direct reflation of underlying geology

Vegetation strongly dependent on the mineral/moisture content of soil

types of vegetation can be linked directly to specific bedrock lithologies.

degree to which soil holds water related to the permeability of the bedrock beneath it.

Question 26

what areas do you use soil and vegetation interpretation

Answer 26

areas not covered in superficial deposits

not been heavily cultivated

Question 27

what are superficial deposits

Answer 27

youngest geological deposits

formed during the Quaternary period

Question 28

short green grass indicates

Answer 28

soil well drained and developed

Question 29

long grass and reeds

Answer 29

poorly drained soils

Question 30

heather and short patch grass

Answer 30

well drained but poorly developed soils