the forming soil

Question 1

what are the five soil forming factors

Answer 1

climate (cl)
biological activity (o)
relief (r)
parent material (p)
time (t)

Question 2

describe zonal soils

Answer 2

adequate time for formation
normal relief landscapes (flattish)
ordinary silicious parent materials (often sedimentary rock)
distinguishing features due to climate and associated vegetation

Question 3

describe intra zonal soils

Answer 3

soils developed on different parent material or have special effects induced by fluctuating water table or topography

Question 4

describe azonal soils

Answer 4

soils that have not had sufficient time to mature due to geological processes such as fooding or avalanches which result in the dumping o new parent materials for example the rangetiki soils

Question 5

what are biosequences

Answer 5

they are formations due the different types of vegetation growing on them ie eg cup podzols

Question 6

what are toposequences

Answer 6

soil associations that have formed in response to changes in relief

Question 7

what is physical weathering and how does it lead to chemical weathering

Answer 7

its the breakdown of material into smaller material = increase SA = increased reactivity = chemical weathering

Question 8

an example of physical weathering

Answer 8

mechanical abrasion due to rivers having strong flows or flooding to the deposition of alluvium and creation of degradation terraces

Question 9

what is translocation

Answer 9

the redistribution of dissolved minerals or dissolved particles through porous rock or soil very important in podzol formation
eluviation = removal (e horizon)
illuviation = deposition (B horizion)

Question 10

what are 4 different chemical weathering processes

Answer 10

hydrolysis
leaching
chelation
gleying

Question 11

what is hydrolysis

Answer 11

the reaction between hydrogen and hydroxide ions dissovled in water with the chemical elemnts in the mineral lattice within rocks . H+ ions are exchange with cations within the rock and diffused into the soil these cations are then either taken up by plants roots or lost n the soil via leaching in order for hydrolysis to continue these cations must be removed to prevent equilibrium

Question 12

what increases hydrolysis (3)

Answer 12

• low ph as there are more h+ ions to replace cations
• fine textured soils due to increased SA thus increased reactivity
• higher temps as particles have more energy so reactions are more likely to take place

Question 13

what is leaching

Answer 13

the downward or lateral movement of cations released during hydrolysis

Question 14

what can impact leaching rates

Answer 14

can be increased with increased rainfall
can be decreased if lots of vegetation is present due to the roots taking up the cation ions faster than the leaching process can occur

Question 15

how does leaching effect hydrolysis

Answer 15

leaching allows the hydrolysis process to continue as it prevents equilibrium
its is also a cycle Increased leaching = increased soluble cations lost = increased acidity = increased hydrolysis

Question 16

what is chelation

Answer 16

chelating agents produced by alterations of humus by plant acids or excreted by lichens bind with cations in rock which make them more easily removed during the hydrolysis process

Question 17

what is gleying

Answer 17

it is when the soils are a blue - grey colour due to a high perched water table meaning they are predominately staurated this removes the oxygen and denitrification can take place

Question 18

3 main classifications of nz parent materials

Answer 18

Igneous rock
sedimentary rocks
metamorphic rocks

Question 19

what are igneous rocks

Answer 19

formed from the cooling of molten magma they are a source of primary minerals

Question 20

what are sedimentary rocks

Answer 20

formed from the burial and compaction of weathering products and resistant primary minerals glued together by secondary minerals such as clay and oxides

Question 21

what are metamorphic rock

Answer 21

deeper burial compaction and heating of sedimentary rocks new materials are formed due to the formation process

Question 22

what are the least resistant primary minerals

Answer 22

pyroxenes
olivines
amphiboles

Question 23

what are the more resistant primary minerals that also make up sedimentary rocks

Answer 23

feldspars
micas

and quartz is the most resistant

Question 24

Describe aggradation and provide an example off its occurrence in the Manawatu

Answer 24

Aggradation is the process of alluvium accumulating and building up landscapes due to cold periods in the climate cycle. These are the older terraces we see around the area for example the ohakine terraces which is the most recent aggradation terrace. There is a lack of vegetation thus more erosions taking place and being deposited in rivers which due to the cold temperatures are often not flowing as fast or strongly and accordingly cannot get rid of the accumulating eroded material, so it accumulates on the landscapes instead. Winds also plays a large role as material is carried by the strong forces and deposited on the landscapes also (losses).

Question 25

Describe degradation and provide an example off its occurrence in the Manawatu

Answer 25

Degradation is the cutting into landscapes and formation of degradation terraces, the most recent in Manawatu being the rangitikei soils. This happens when the climate is warming during the global climate cycle, ice has melted and accordingly the rivers are flowing quicker and stronger. Warmer climates means vegetation is growing again and thus erosion is less so the rivers are able to remove the material sufficiently. However, the strong rivers begin cutting in to the landscapes due to the erosion being removed faster than its coming in thus the establishment of these degradational terraces