Geomorphology methods Flashcards
(71 cards)
1
Q
key term: rock
A
Rock that is not deliberately altered by humans but often indirectly through climate change processes and air pollution
2
Q
Key term: Cultural rock
A
rock that stayed in original environment but the rock material shows deliberate human artistic/cultural/socially meaningful traces
3
Q
Key term: stone
A
rock removed from its original environment and used in the construction of cultural heritage or domestic infrastructure
4
Q
what is direct data?
A
a direct data source is one that can be gathered from without having to go to a third party – ‘original source data’
5
Q
what is proxy data?
A
an indirect measure of the desired outcome which in itself is strongly correlated to that outcome. Commonly used when direct measures of the outcome are unobservable and/or unavailable
6
Q
what is modelled data?
A
data from models
7
Q
what are the characteristics of a lab experiment?
A
Max control/min realism
Short and medium temporal scale
Nano and micro spatial scale
8
Q
characteristics of field measurement - monitoring and analysis?
A
Min control/max realism
Short-, medium- and long-term temporal scale
9
Q
Characteristics of mapping?
A
Max control/various realism
Always subjective
Nano-, medium and macro scale
10
Q
Characteristics of modelling studies ?
A
Control depends heavily on input data
Often only a proxy to reality
Temporal scale: any and spatial scale any
11
Q
what is a model?
A
an abstract mathematical representation of process, device or concept – uses a number of variables to represent inputs, outputs and internal states
12
Q
How long is Chesil Beach?
A
18 miles long
13
Q
What type of coastal feature is Chesil Beach described as?
A
A pseudotombolo
14
Q
What was the original source of material for Chesil Beach?
A
Sandy deposits from Lyme Bay, transported by rapid rising water levels at the end of the last ice age
15
Q
Sandy deposits from Lyme Bay, transported by rapid rising water levels at the end of the last ice age
A
5000 years ago, having been driven further east starting 7000 years ago
16
Q
Where did large masses of gravel come from to help form Chesil Beach once sea levels stabilised?
A
From eroded cliffs at East Devon
17
Q
Why is Chesil Beach considered sensitive to environmental changes?
A
Because it has no replenishment
18
Q
How is Chesil Beach vulnerable to climate change?
A
Risk of increased flooding, loss of coastal defence, and geological loss impacting tourism
19
Q
What geological feature is studied at Portland Bill?
A
A shore platform
20
Q
What type of rock forms the geology at Portland Bill?
A
jurassic limestone
21
Q
Name some natural forces that interact with the Jurassic limestone at Portland Bill.
A
Waves, tides, wind, and biological activity
22
Q
At Portland Bill, what shapes the coastline and leads to varying levels of erosion?
A
The interaction of force (Waves) and resistance (rock)
23
Q
What happens when forces exceed resistance at the coast?
A
Dynamic eroding landscapes emerge
24
Q
Why is Portland Bill considered a good place to study coastal dynamics?
A
It has unique geology (Jurassic limestone), high energy forces (waves, tides and winds), and historical importance for navigation
25
What digital tools can be used to record landscape features when investigating coastal impacts?
Photogrammetry and Lidar
26
How can resistance be measured when investigating coastal impacts?
Use a Schmitt hammer to measure rock hardness
27
When did hand working largely stop at Tout Quarry?
By 1982
28
What has Tout Quarry become since quarrying stopped?
A natural reserve for limestone loving plants, butterflies, and common lizards
29
How do artists contribute to Tout Quarry?
They frequently give back through their creativity, sculpting and carving out of the limestone
30
What can be studied at Tout Quarry?
Sculpture, geology, ecology, place history, and time
31
What concept was explored through participatory mapping conducted at Tout Quarry?
Maps as political objects, reflecting and reproducing the contexts of their creation
32
Historically, what were maps often used for?
To claim ownership over a landscape and to dispossess indigenous communities
33
What is counter-mapping?
Resistance that challenges dominant power relations and allows local and indigenous communities to reclaim space, land, and resources
34
What is the impact of quarrying on ecology?
It causes habitat destruction and pollution
35
How has Tout Quarry's ecology changed since quarrying stopped?
It has regenerated as a nature reserve
36
What is the role of lichens discussed in relation to Tout Quarry?
Their contribution to biodiversity and site regeneration
they are complex ecosystems with both harmful and protective effects
37
name the methods that can be used for investigating at the site of Tout Quarry
Visual, haptic, and small observation, photo documentation, moisture measurements, and hardness measurements
38
when might lab-based methods be preferred for research?
When seeking an understanding of a single and controlled mechanism, for reduction of complexity, or when dealing with low reality levels. It's important to consider the context of the study
39
What is one purpose of disseminating research activities?
It is a way to engage the public with research
40
What are the key advantages of using non-destructive methods for investigation?
They preserve the integrity of the investigated structure.
Can be applied on a larger scale
Applied more frequently
Often less expensive than the lab based methods – easy access
May not require special expertise
Often immediate results with less data processing
Portable (ideal for immobile structures)
41
Disadvantages of using non destructive methods?
*Often proxy data is generated (higher level of uncertainty, variability and affects accuracy
*Might be affected by material properties/ conditions (mineralogy, porosity and contaminants etc)
*There may not be a standard to the use of the method (effects the reproducibility and repeatability)
*High number of readings may be required = time consuming
*Might be affected by the environmental climate
*Operator variance higher
42
Advantages of using a destructive method?
* Higher level of certainty, accuracy
* Deep insight into material properties and conditions
* Potentially less effected by climate
* More likely a standard practice that can be followed
* Might be portable
* Might be used as a standalone method
43
Disadvantages of destructive methods?
* Affects the integrity of the investigated structure
* Applied on a smaller scale
* Applied less frequently
* More expensive
* Require specialist expertise
* Operator variance (always needs to be considered)
* MORE DATA PROCESSING MAY BE REQUIRED – longer time scale
44
What factors should be considered to ensure data is reliable and representative when collecting it?
Considerations include the sample type (number of samples, natural vs artificial), spatial and temporal scale, sampling bias, and sample size
45
What does OSL stand for, and what is it primarily used for?
OSL stands for Optically Stimulated Luminescence.
It is a chronological method used extensively in archeology and earth sciences.
It is primarily used to date the timings of sediment deposition, such as fluvial sediments or dust deposits
46
What is the basic principle behind how OSL works to date sediment?
OSL is based on the emission of light.
Naturally occurring radioactive elements within sediment release radiation.
When the sediment is buried, this radiation accumulates within the rock strata or mineral grains over time.
When the sediment is later exposed to light, the accumulated radiation is released.
By analysing how much radiation is delivered when the sediment is 'bleached' (exposed to light), one can estimate how long the sediment has been buried.
47
How is the age of a sediment sample calculated using OSL?
The age is calculated using the formula:
Age = paleodose / dose rate
48
Describe the initial steps for collecting samples for OSL dating.
Samples must be collected so that they haven't been exposed to light, and they must remain light tight during transport from the field to the lab.
Samples are typically collected from sediment exposure faces. For deeper deposits, drilling or coring can be used.
49
How are OSL samples stored and why is a portion removed from each end of a core?
Samples are stored in black tubing to maintain darkness and prevent bleaching.
If a sample is collected using drilling/coring, 2-3cm is removed from each end of the core because these ends may be light contaminated.
50
What is 'dose rate' in the context of OSL dating?
The dose rate is the rate at which radiation is emitted from the sediment matrix.
It involves evaluating how much alpha, beta, and gamma radiation is emitted
51
Outline the process for preparing a sediment sample for OSL dating measurements.
The goal is to isolate the purified quartz fraction of the sediment. This is done by treating the sample with hydrochloric acid and hydrogen peroxide to remove organic carbonate material.
The sample is then sieved to get a specific grain size, followed by further grain refinement and re-sieving
52
How are OSL measurements made, and what are the two main tests or steps performed before determining age?
Measurements are made using a luminescence reader, which stimulates quartz grains using LEDs and measures the amount of radiation emitted
two tests/steps are performed:
1.
Suitability test: This tests for the optimal temperature for measurement. A known dose is given to the sample, and the protocol is performed to see if the dose can be recovered.
2.
Calibration: Stimulation with LEDs releases the trapped radiation. A calibration curve is created, and the natural luminescence signal is plotted here to calculate the equivalent dose. Grains are screened using a set of rejection criteria.
53
How is the dose rate for OSL dating typically measured?
The dose rate is measured using ICP-MS (Inductively Coupled Plasma Mass Spectrometry)
54
what is a key driver of rock and stone breakdown, and why are moisture metres crucial in studying this?
Water moisture is identified as a key driver of rock and stone breakdown.
Moisture metres are crucial to determine the distribution of water content on a spatial and temporal scale.
55
Describe the working principles of resistance-based moisture metres.
Resistance-based moisture metres rely on the electrical resistivity of materials.
Electrical resistivity is the degree to which a material impedes the flow of current.
As moisture content increases, the electrical resistance increases.
These metres must be calibrated before use.
56
Describe the working principles of capacitance-based moisture metres.
Capacitance-based moisture metres rely on the dielectric constant or permittivity of materials.
Water has a high permittivity, while porous materials have low permittivity.
Permittivity is defined as the ability of a substance to hold an electrical charge.
Increased moisture leads to increased capacitance readings
57
What is a major limitation of both resistance-based and capacitance-based moisture metres?
A major limitation is that these methods are measuring changes in electrical resistivity and capacitance, NOT an absolute measure of the moisture content within an object
58
What factors should be considered when using resistance or capacitance-based moisture metres, as they can affect readings?
Consideration must be given to operator and material variance, environmental effects, and material inherent factors such as salt content and petrophysical properties.
All of these will affect the readings
59
What are 'exposure blocks' and what are they used for in studying weathering?
Exposure blocks are uniform slabs of certain rock that are left in an environment for an extended period.
They are used to measure weathering rates, processes, and chemical breakdown.
They allow for the comparison of breakdown rates in different environments like deserts, rivers, hillslopes, coastal waters, and urban areas
60
What are some limitations of using exposure blocks in the field to study rock weathering?
Some rocks take a long time to break down, making them difficult to study within one human lifetime or solely in the field.
▪
Weathering is rarely linear, meaning rates and processes are not consistent over time, making it difficult to extrapolate findings over longer periods like centuries or millennia.
▪
Weathering can occur without any physical signs of visible change (hidden internal change).
▪
There are many variables involved in the field, making it difficult to determine exactly what or how rocks are being weathered
61
How can lab-based simulations help overcome limitations associated with exposure blocks?
Lab-based simulations can overcome some of the limitations by allowing environmental variables to be fully controlled.
Samples can be subjected to processes like heating/cooling, wetting/drying, and freezing/thawing, often in combination with salt.
These simulations can also be sped up to condense years' worth of weathering into months or weeks
62
What equipment can be used to measure rebound hardness?
Impact hammers such as Equotip and Schmidt hammer can be used
63
what can be used to measure surface roughness?
TRACEiT
64
What does ICP-MS stand for, and what is its primary purpose?
ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry.
It is an analytical method that allows the investigator to understand the chemical makeup of a sample by determining how much of each element is present
65
Briefly explain how ICP-MS works to identify and quantify elements in a sample.
By coupling a mass spectrometer to a powerful source of energy (the plasma), it's possible to analyse almost the entire chemical constituents of a sample.
The plasma acts as an ioniser, stripping electrons from atoms to give them a positive charge.
These positively charged ions are then funnelled into a detector.
The mass spectrometer can be set to look at any mass and counts the number of positively charged ions hitting at each mass.
66
How does ICP-MS convert the raw ion count data into useful concentration values (like ppb)?
By analysing samples of a known concentration (typically in parts per billion) and creating a calibration curve, the counts per second data can be converted into useful ppb values, telling you exactly how much of each element is in the sample
67
What is satellite imagery used for in studying landscapes?
give example
Satellite imagery is used to detect features and track changes over larger spatial and temporal scales.
For example, Google Earth time lapses demonstrate the changing surface configuration of the planet over the last 40 years
68
What kind of information can spectrometric analysis satellites provide about a landscape?
Spectrometric analysis satellites can detect features such as the type and composition of bedrock, as well as soil extent and vegetation health.
This helps track the landscape's development over time
69
What software is mentioned for classifying regions based on satellite data and creating maps?
ArcGIS software is mentioned for classifying regions into terrestrial categories and creating spatially represented maps based on differing colours of different biomes or ground-types
70
What is the basic principle behind infrared imagery as described by the Stefan-Boltzmann Law?
The basic principle is that energy emitted by a body is directly proportional to the 4th power of the temperature of the emitting body.
This means hot bodies emit more energy than cold bodies.
Sensors detect these infrared wavelengths
71
What are some potential problems or limitations when using infrared imagery to determine temperature?
Problems include that the emissivity of an object depends on a complex range of factors, such as density and thermal contact.
This may create a difference between the true and apparent temperatures
