dynamic enviroemnts

glacier hillslope

- The slopes of mountains boarding a glacier where rock, snow and ice move downhill

carbonation

Atmospheric carbon dioxide dissolves in water to make a weak acid. 

- In some rocks this acid reacts readily to give calcium bicarbonate Ca(HCO3)2 which is soluble so splits into ions that can be dissolved 

-Forms karst- cracks in caves where water flows

acidification 

Acid may form in rain or groundwater e.g. sulphuric and nitric 

hydrolysis

Water itself can react with rocks, which can break down olivine  

-Can chemically react with some minerals without breaking bonds by fitting into the mineral structure to change the properties of the minerals  

oxidation

Minerals rich in iron can react with oxygen  

-Can be in air or dissolved in water 

-Leaves characteristic red and yellow 

-fastest at the edge of rocks  

expansion and wedging

Forces rocks to break apart, e.g. root growth, wetting and drying, thermal, freeze thaw and burrowing

abrasion 

Transported rocks and sediments grind against other surfaces wearing them down over time to shape new landforms

plucking

When water seeps into cracks in the rock, freezes and expands causing blocks of rock to become frozen onto the base of the glacier so when the glacier moves forward the rocks are free from the glacier by being plucked out 

glacier

A thick mass of recrystallised ice that lasts all year long and flows via gravity  

-Mountain glaciers flow from high to low elevation  

-When ice is thick and dense high pressures create stress that causes ice to deform 

and form u shaped valleys 

ice sheets 

Large bodies of glacial ice covering more than 50,000 square kilometres of land e.g. Greenland and Antartica

forming glaciers

-Snow is transformed into ice 

-Delicate flakes accumulate 

-Snow is buried by later falls 

-Compression expels air  

-Burial pressure causes melting and recrystallisation  

-Over time, firn melds into interlocking crystals of ice 

watermelon snow algae

protective cyst layer from bright sunlight and UV radiation

cryoconite hole 

Holes in a glaciers surface caused when sediment is carried by wind onto the glacier as the sediment is darker than the ice it warms up the sun to melt into the glacier, have access for sun and water meaning a variety of life can survive inside e.g. fungi ,microorganisms and bacteria 

ablation and 3 reasons why

Loss of mass from a glacier through: 

-Melting 

-Sublimation, low humidity turns ice directly into water vapour  

-Iceberg calving, where large chunks of ice break off the edge of a glacier forming new icebergs  

 

zone of accumulation

net snow addition

zone of ablation 

net snow loss

eg groner glacier switzerland 

moraine

A ridge or hill made of loose glacial till left by a glacier, can be from when a glacier flows by or when a glacier recedes 

-Changes overtime  

-Lateral 

-Terminal 

-Medial  

 -Shows history of where the glacier has been at the terminal moraine 

glacial deposition

-Till- Unsorted mixture of clay, silt, sand and boulders deposited by a glacier  

-Erratic's – Rock transported by glaciers from originally a different area  

-Marine sediment  

-Glacial outwash 

-Glacial lake bed sediment 

-Drop stones- Largest sediment deposited 

ergs

Seas of sand 

-20% of Sahara desert  

-Dune fields of 125km 

-Primarily in northern Sahara  

clasts

Sediment grains  

-Forms clastic sedimentary rocks by weathering of bedrock, erosion to remove grains from bedrock, transportation, deposition, lithification to turn into hard rock 

sphericity 

how much a rock looks like a sphere

grain size

Clastic sediments and sedimentary rocks are classified by diameter  

 -Using the Wentworth scale 

conglomerate

Rounded pebbles High  

energy rounded 

breccia 

angular pebbles 

sorting

Measure of the spread of grain size 

-Tells us about transport/deposition 

-Can influence the porosity and permeability of a rock 

-Wind is highly effective at producing well sorted sediments  

-Use grain chart 

porosity

Pore space in a rock for air, water, gas, oil

-Porosity= Volume of voids/total volume  

-Given as a decimal or percentage 

permeability 

How easily liquid flows through pores

-Connections between pore spaces and fractures help increase permeability 

-Mud and clays with small gaps between particles help decrease permeability 

 

ripples landform

Form with ridge crests at right angles to the prevailing wind 

dune

windblow accumulations of sand eg free and impeded

regs

Stony desert plain 

-70% of Sahara desert 

deflation mechanism

the removal of sediment 

-very strong winds required to transport sand size grains, usually coarser grains left behind 

-leaving lag deposit 

silt/clay accumulation mechanism

-Weathering forms rocky fragments on the surface of exposed bedrock 

-Silt and clay are blown in from far away and accumulate between the rocks, rainwater causes fine particles to percolate down beneath the rocks  

-Over time rocks break apart and form a tightly fitting stone surface  

hamada

Barren, rocking plateaus where the finer sediment has been removed  

Eg Acacus mountains Libya

green sahara

-The Sarah had extended periods of abundant rainfall lasting thousands of years in the pluvial period in Africa  

-Productive for vegetation and animals

paleo shoreline

wave action erosion 

 of dunes where there used to be water

west African monsoon

-African land mass heats up faster than the oceans 

-Warm air rises, creating a low pressure zone over the continent 

-Drives an inflow of moist air from the Atlantic Ocean, bringing rains in  

Why was Sahara greener 9000 years ago? 

-Eccentricity, how much the earth's orbit around the sun deviates  

-Tilt, angle of earth 

-Precession, the wobble of earths rotational axis  

sustainability

Meeting the needs of the present without compromising the ability of future generations to meet their own need 

pore space

The measure of pore space in a material  

-In some rocks and unconsolidated sediments there is space between the individual particles that can fill with water, gas, and fluids  

-However in crystalline rocks all the particles are connected and there is no space for water   

fractures/cracks 

Some rocks have cracks and fractures that run through them so water can be stored in these spaces  

-Common in tectonic regions   

aquifer 

Is a geologic unit that can store and transmit water 

Type: Unconfined, confined, perched

confining layer

Is a geologic unit that does not allow water to move through it quickly 

unconfined aquifer

-Porous permeable rock 

-Open to more water 

-No rocks above or below 

recharge area 

Where water 

 enters the aquifer, only recharge 

 in specific areas  

potentiometric surface

The level that  

water in a confined aquifer would 

 reach if it is depressurised, the well  

needs to be built above this surface 

artesian well

When water rises to the 

 ground surface without needing to pump 

 it, after drilling into a confined aquifer  

perched aquifer

-Above primary water table  

-Collecting water like a bowl  

-Cheaper extension for water as 

 closer to surface  

 

water table

Loosely follows the topography,  generally as a subdued image of the surface  

hydraulic head

A measure of the water pressure above a specific point  

-If its sea level the hydraulic head is a measurement of the pressure of water in rocks, sand or gravel at any point above sea level so water will move from areas where this measurement is higher and lower  

groundwater abstraction 

Process of removing freshwater from underground sources like an aquifer  

-Effects the water table  

cone of depression

- The bowl shaped  

depression in the water table causing it 

 to lower from the pumping of water  

-When abstraction out ways recharge  

groundwater depletion problems 4 answers

-well stops being function

-land subsidence

reduced surface water supplies

-water quality

land subsidence 

now has empty pore space in bed which means land becomes more compressed and lowers the ground level can trigger earthquakes and faults to open 

1 before pumping stresses are in equilibrium from overlying material and water stress 

2suring pumping stresses are not in equilibrium as water pressure is reduced so overlying material is a greater opposing stress 

3 equilibrium is restored by increasing compaction which reduces the aquifer thickness and lowers land surface  

fengcong karst

Roughly conical hills separated by deep, closed depressions, forming continuous terrain of steep slopes and significant relief 

fenglin karst 

Isolated limestone hills rise up above a flat alluvial plain  

-Requires very thick limestone sequences 

-Mature  

doline karst

Depressions found in karst landscapes also known as a sinkhole  

-The initial karstification process 

formation of limestone

- Marine organism use ions dissolved in seawater to precipitate calcium carbonate as the mineral calcite or aragonite 

-These minerals from limestones as protection 

-Ions are a product of chemical weathering reactions on land and are transported by rivers  

clastic sedimentary rocks 

-Physical weathering  

-Roundness and sorting of grains reflects transports and depositional environment  

carbonate sedimentary rocks

-Ions produced by chemical weathering 

-Used in organic or inorganic precipitation of  CaCO3 

non skeltals/non inorganic grains

Spherical-subspherical grains, consisting of one or more regular concentric lamellae round a nucleus like a carbonate 

ooids 

less then 2mm diameter grain 

pisoids

greater then 2 mm grains

limestone matrix

- The fined grained carbonate mud (micrite) that binds together larger grains in the sedimentary rock limestone  

-Grains in micrite (mud) 

carbonate factories 

Majority of carbonate sedimentation occurs in warm shallow seas in the tropical-subtropical belt  

kast

Is a topography formed from the dissolution of soluble rocks such as limestone forming caves and unique surface landscapes  

tectonic uplift 

enables doline karst to evolve into fengcong karst which will evolve higher and higher relief until the base of the doline reaches the base of limestone sequence  

-Water wants to get back to water level so reduces erosion for more uplift  

lateral planation

requires enhanced dissolution of limestone by corrosive water at the level of the water table, which is close to the alluvial plain which leads to undercutting of rounded hills, facilitating the formation of tower like structures  

limestone dissolution

When water passes through limestone dissolving it producing ions in solution

travertine

chemical limestone

when water underground dissolves calcium carbonate

when water reaches surface co2 is released

precipice out mineral forming Caltrate

speleothems 

A structure formed in a cave by the deposition of minerals from water  

-Archives of past climate change as they are slow forming  

-Temperature, precipitation and amount able to be tracked back in time 

-Analysed for their oxygen isotope composition through a mass spectrometer

speleothem radiometric dating

-Cosmic radiation neutrons combine with nitrogen to form radioactive carbon-14 which is taken in by organisms and released once it dies and the ratio can be tracked 

-What carbon-14 that is left can be tracked to find age

speleothems isotopic dating

-CaCO3 in speleothems contains small amounts of uranium 

-Use the uranium decay series to date speleothems  

-Comparing ratio  

-It has a longer half-life then carbon-14 so it can date much older samples

oxygen isotope ratio of layers 

-16O is evaporated from seawater 

-18O is condensed in clouds  

-Leads to progressive enrichment in 16O with latitude and altitude 

-Cooler air massed van hold less water vapour so 18O is preferentially rained out 

-Larger rainfall enables more 16O from higher atmosphere to be rained out  

-Separation of isotopes in the water cycle in fractionation  

amount effect

- A negative correlation between the amount of precipitation and ratio of stable isotopes

coast

area where land and sea meet

coastal zone

Broad term for the area influenced by proximity to the coast  

 

offshore zone 

The portion of the profile where no significant transport of sediment by wave action 

littoral zone

The portion of the coastal profile where sediment can be transported by wave action 

nearshore zone

The portion of the profile extending from the limit of sediment transport by waves to the low tide line

beach

The portion of the profile subject to wave action and which is exposed sub aerially at least part of the time 

foreshore

The portion of the beach subject to wave action during non-storm conditions  

backshore

The part of the beach only subject to wave action during storms  

surf zone 

The zone of broken waves extending from the breaker zone to the foreshore

swash zone

The zone of wave rub up on the beach and return of water in the form of backwash

intertidal zone

The zone of the beach influenced by the tide, region between high and low watermark, most at risk to sea level rise

continental shelf 

The submerged gently sloping edge of a continent that extends from the coastline under relatively shallow water before dropping off steeply at the continental slope  

4 environmental boundary conditions

geology

sediments supply

human activity

external forces of tides and waves

4 dominant deep sea sediments 

1 Red clays 

2 Siliceous ooze 

3 Calcareous ooze 

4 Terrigenous sediments 

red clay

Mostly windblown sediment  

-Quartz and clay minerals  

-Volcanic and cosmic dust  

-Brown colour reflects oxidation of iron, helped by snow deposition on seafloor 

-Slow deposition has a lot of time to oxidised 

siliceous ooze

-Biogenic opal SiO2.nH2O 10% water  

-Made of diatoms and radiolaria

diatoms 

-sillieous ooze

-Unicellular algae with opal shells 

-Few to 200um diameter 

-Abundant in high latitude  

-Phytoplankton 

-Produce 25% of all oxygen on earth

radiolaria

-siliceous ooze

Zooplankton with siliceous tests 

-50-300um diameter 

-Dominate component of low latitude 

3 controls of silicous ooze

1 Supply, high rain rate of biogenic silica create areas of high productivity  

2 Preservation, seawater is universally undersaturated with respect to opal so rapid burial required 

3 Dilution, silica is not swamped by carbonates or terrigenous material  

 

calcareous ooze

-calcium carbonate 

-coccolithophores

-foraminifera

-pteropods

calcium carbonate solubility

In cold waters, under high pressure, in acidic waters  

 -Solubility increases with depth in the ocean  

calcite compensation depth

The horizon in the water column beneath which no calcite can be preserved in ocean sediments 

-To cold, high pressure, deep calcium just dissolves immediately 

 

terrigenous sediments 

From rivers, gravels, sands, silts and clay  

-Deposited on continental shelves and slopes bordering ocean basins  

-Sources from, physical weather and erosion of land 

-Transported to oceans by rivers, glaciers and wind 

 

ice rafted debris

Deposited on seafloor when icebergs melt, dropping their sediment load 

-Found at high latitude