Trivia

Question 1

Describe the formation of intrusive igneous rock. Give one example.

Answer 1

Intrusive igneous rock is formed of magma that has cooled slowly underground. E.g. Granite

Question 2

Describe the formation of extrusive igneous rock. Give an example.

Answer 2

Extrusive igneous rock is formed of lava that has cooled rapidly on the Earth’s surface. E.g. Dolerite

Question 3

Describe the formation of the crystalline structure and resultant weathering characteristics of intrusive vs extrusive igneous rock.

Answer 3

Intrusive igneous rock is formed of slowly cooling magma and so forms large crystals that are more weathering resistent while intrusive igneous rock is formed of rapidly cooling lava and so form a smaller crystalline structure and are therefore more susceptible to weathering.

Question 4

Describe the formation of sedimentary rock. Give an example.

Answer 4

Sedimentary rocks are formed of deposited minerals; generally in water; being compressed by the weight of material deposits above them until they are lithified. e.g. limestone

Question 5

What is the difference between lithification and petrification?

Answer 5

is that petrify is to harden organic matter by permeating with water and depositing dissolved minerals while lithify is to turn sediment into solid rock

Question 6

Describe the formation of metamorphic rock. Give an example.

Answer 6

Metamorphic rocks are either of the igneous; sedimentary or previous formed metamorphic rock being altered by heat; pressure or a combination of the two to form a new rock type.

Question 7

What is the difference between lava and magma?

Answer 7

Lava is molten rock on the earth’s surface while magma is molten rock below the earth’s surface.

Question 8

What determines the crystal size of igneous rock?

Answer 8

The rate of cooling.

Question 9

What is the difference between weathering and erosion?

Answer 9

Weathering is the breakdown of rock in situ where erosion is the movement of that weathered material or the entire rock.

Question 10

Identify two conditions that make an area more susceptible to erosion.

Answer 10

Poor vegetation coverage. Soil grain size and soil type.

Question 11

What two factors directly affect soil erosion?

Answer 11

The factors having a direct effect on soil erosion are atmospheric precipitation (water erosion) and wind (wind erosion).

Question 12

Identify 2 counter-erosion measures.

Answer 12

Mattress/brush packing whereby branches are cut and used to cover an area in order to manage impact from rain and rain-water runoff. Use of swales. Use of gabions. Any similar water runoff management technique.

Question 13

What is a bolster?

Answer 13

Bolsters are humps in the road that channel water runoff toward the side of the road

Question 14

What is a mitre drain?

Answer 14

Mitre drains channel rain water (usually from bolsters) into the vegetation that can absorb the impact of that water.

Question 15

What is meant by topography?

Answer 15

Topography is the description of the land with regard to height above sea-level.

Question 16

What is soil?

Answer 16

Soil is a mixture of abiotic weathered material, organic matter; minerals; gases; liquids; and organisms that together provide a medium that supports life.

Question 17

How does soil impact plant growth?

Answer 17

Soil type affects drainage which in turn affects nutrient retention in those soils. Heavier grained soils are well drained and well leached where finer grained soils retain nutrients and moisture. This affects what plants are able to grow and thrive.

Question 18

Describe 3 ecologically distinct regions of Londolozi and their associated plant communities.

Answer 18

The black turf savannah of the south western boundary of the reserve is heavily waterlogged; preventing encroachment of woody growth and promoting large tracts of nutrient rich grasses. Guarries are the main woody-growth species found on the large sodic area around Sunset Bend where the soil is heavily calcified and extremely nutrient rich.

Question 19

What is an ecotone?

Answer 19

An ecotone is a transition area between two biological communities. It is where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems)

Question 20

What is a catena?

Answer 20

A catena is a sequence of soils down a slope; created by the balance of processes such as precipitation; infiltration and runoff.

Question 21

What is a seepline?

Answer 21

An area where water that has drained through courser grained soils to an impermeable rock or finer grained soil layer from where it is channeled horizontally to the slope of a catena and emerges at the surface to form a waterlogged band running horizontally along a slope.

Question 22

Describe 2 vegetation types assoiciated with seeplines.

Answer 22

Silver clusterleaf – Terminalia sericea and Herringbone grass – Pogonarthria squarrosa

Question 23

Why did Tinley advise that roads on seeplines should be re-routed?

Answer 23

Roads that cut through these areas should be re-routed in order to prevent drainage through “canalling” whereby the soil moisture is drained through the grooves of the tyres which results in the drying of these soils and encroachment of woody plants that would otherwise not be able to establish a position in that water-logged soil that maintains nutrient rich grasslands for grazers.

Question 24

Describe the effect of introduced timber plantations on seeplines and associated vegetation.

Answer 24

Exotic timber plantations usually make use of fast-growing trees that have an extremely high water demand. What this results in is these trees tapping into the underground water systems and draining that water that would normally flow up toward the seep lines. This dries out the seeplines and allows for encroachment of other woody plants otherwise held at bay by the waterlogged soils.

Question 25

How is a sodic area formed?

Answer 25

A sodic site is formed by the slow movement of salts and nutrients down a catena sequence and collecting at the base of this system. This results in a hugely nutrient rich area where the plants that grow on here; in particular the grasses; are sought after by grazing animals that over utilize the area. This over-utilisation results in extreme compaction of the surface layer of these areas; “capping” the underlying soil and preventing much woody growth besides guarris which can handle these conditions and various nutrient rich grasses.

Question 26

Name two identifying characteristics of a sodic site.

Answer 26

An abundance of Guarri trees. Well utilized flat areas of open ground; often with exposed almost white soils.

Question 27

Why are sodic sites considered to be so sensitive?

Answer 27

The formation of the “crust” through compaction by animal hooves means that ground is extremely susceptible to sheet erosion in heavy down pours as it does not absorb the rainwater which instead runs over it in sheets; gathering momentum and eventually stripping the top layer of that system. Once through the crust; further erosion happens rapidly as the dry unvegetated soil underneath is easily taken away eventually resulting in gulley erosion which can eventually destroy the entire site.

Question 28

Identify 2 prominent sodic areas on Londolozi.

Answer 28

Along Taylors river road between Tsalala and Elmons Kraal. To the south of Upper River Road to the east and west of Vomba.

Question 29

What do you understand by the term “black turf soil”?

Answer 29

Black turf soil is extremely fine-grained clayey soil. It is extremely water and nutrient retentive meaning that these areas are often open as the woody growth is held in check by the waterlogged nature of the soil, the same mechanism that occurs in seeplines. The grasses that grow on here are nutrient rich and valuable to grazers. This clay soil can easily disable a Landover and driving on this soil should be avoided at all costs.

Question 30

Describe the formation of granite and gabbro.

Answer 30

Magma cools beneath the earth’s surface; cooling slowly and resulting in the formation of course grained rocks with a crystalline diameter of 1 - 1.25mm. the difference in these rock types is the result of the slight difference in the rate of cooling.

Question 31

Describe the soil types associated with granite/gabbro.

Answer 31

The soils associated with the weathering of granite/gabbro are course grained; well leached in the presence of high rainfall and quite acidic.

Question 32

What is a kopjie and why do they stand out from the rest of the landscape?

Answer 32

Kopjies are hills composed of hard-weathering rock types such as dolerite intrusions that project from the landscape as the rest of the landscape has eroded more quickly over previous millennia; leaving the kopjie exposed.

Question 33

What are dolerite dykes and where can they be found on Londolozi?

Answer 33

Dolerite dykes are formed by an upwelling of magma which found its way through a linear crack in the surface layer of rock. There is a dolerite dyke running East to West through the centre of the Marthly property.

Question 34

How do dolerite dykes affect the vegetation of Londolozi?

Answer 34

Dolerite dykes have resulted in course grained soils; leached of nutrients by the summer rainfall; resulting in the colonization of these areas by broad leaved trees such as Marulas that are able to draw water and associated nutrients from deep below the surface.

Question 35

How were the Drakensberg Mountains formed?

Answer 35

Over 160 million years ago; Gondwanaland was still intact. As what would become India and Antarctica broke away enormous cracks formed on the Eastern edge of the Africa. Rather than explosive eruptions; thick lava flowed and cooled and flowed and cooled; adding from 30cm to 50 metres of lava at a time from these fissures. Throughout 20 million years these flows built up a deposit of basaltic rock; over 1;5 kilometres thick in some places; covering an area extending from inland of present day Lesotho over most of KwaZulu-Natal as far as Mozambique and the Indian Ocean.

Question 36

How is a caldera formed? Name an example in RSA.

Answer 36

A caldera is a volcanic feature formed by the collapse of a volcano into itself; making it a large; special form of volcanic crater. A caldera collapse is usually triggered by the emptying of the magma chamber beneath the volcano; as the result of a large volcanic eruption. A well-known example in RSA is the Pilansberg Caldera.