Geob chapter 2 GOOG

What is a numerical model and how would it be useful to a geomorphologist

A numerical model is an equation to predict certain processes based on known values and repeated experiments

What is weathering rind and how does it change over time

A weathering rind results on a rock when the rock has been exposed to the atmosphere and shows the last time that the rock surface was fractured or abrade. Weathered material is often red and oxidized

Explain the difference between active remote sensing and passive remote sensing

Active remote sensing sends a signal, receives it and analyses it. Passive remote sensing measures the amount and wavelength of energy emitted from the Earth's surface.

What happens to the radiocarbon content of wood after a tree dies and is buried in a river terrance

After a tree dies and is buried in a river terrace the radiocarbon content of the wood is preserved and decays slowly based on its half life

How have changes in mapping technology over the past decade changed the field of geomorphology?

Automated much of the landscape analysis tasks that were done manually

Explain how calibrated relative dating methods differ from isotopic dating methods and predict which one is likely to give more precise and accurate ages

Calibrated relative dating methods differ from isotopic dating methods as they are more of an estimate based on the timing of known events in different regions. Those values are purely estimated based on the observations seen in similar situations. Isotopic dating methods are more accurate and predict dates based on the amount of certain isotopes which are present in a material based on their know half life.

Explain what DEM is and how it can be made

DEM: digital elevation model each data point represents a the average elevation for a pixel. remote-sensing data collected by sensors on satellites were manipulated to extract topographic information. LiDAR and SRTM data is used

What is dendrochronology and how does it work?

Dendrochronology is the measurement and counting of tree rings to determine to age of the tree based on the assumption that a tree will grow a new ring every year.

Explain how the atmosphere testing of nuclear weapons in the past helps today's geomorphologists

Isotopic methods measure cesium-137, which was released to the atmosphere during the 50s and 60s during testing of nuclear weapons- it binds whether an area is eroding or aggregating. measurements of the amount of caesium-137 allow for precidiction of the age of a landscape and the rate of certain changes

What dating technique is frequently used to quantify the age of young volcanic rocks

K/Ar dating

Explain the difference between relative dating methods and numerical dating methods

Relative dating methods describe the age of a certain feature/landform in relation to another while numerical dating models approximate the age of a feature.

What is rock varnish , where would you find it, and how does it probably form?

Rock surface occurs when the surface of a rock is exposed to the atmosphere. Fe and Mn build up, which is though to be the result of biological activity

Clearly state the difference between sediment generation and sediment yield

Sediment generation: the amount of sediment created in a river, forms and erodes from its parent material Sediment yield: the rate at which sediment is exported from the landscape

What are SRTM data and why are they important to geomorphology

Shuttle Radar Topography Mission (SRTM), yr 2000, first worldwide digital topographic data set, resolute approx. 90 m per pixel & covering latitudes less than 55 degrees. Mapped areas of the Earth for which topographic data has never been gathered & for areas which persisted with cloud cover that had previously prevented aerial photography.

How does LiDAR work and what is it useful for geomorphologically

Sweeping laser pulses across the landscape detecting the timing of their returns. produces local data sets covering tens to thousands of square kms. Can be post processed to remove effects of vegetation and buildings. Can map outcrops and fine-scale landforms with cm scale precision. repeated surveys detect subtle changes over large areas and allow calculation of rates of mass or addition

Explain how laboratory and field experiments can help us to better understand surface processes

They re create certain conditions to attempt to determine how certain processes and outputs affect surface processes and better understand their causes.

Explain the physics underlying luninesence dating methods

electrons become trapped in crystal lattices of minerals like quartz. When the sample is heated or stimulated by light the electrons are released and they give up energy as photons, emitted photons can be counted and dates calculated if the intensity of irradiation and the radiation sensitivity of the minerals are known

Define integration time and explain why it is important to geomorphology

integration time is the time over which the resulting rate is averaged. It aids in acknowledging the assumptions underlying rate calculations

How are lichens used to date geomorphic features?

it can be measured how fast lichens grow on certain surfaces over time and by measuring the size of lichens on a certain surface on can estimate the amount of time which a certain geomorphic feature has been present

List three relative Dating methods

landform degredation, rock weathering and soil development, rock varnish, calibrated relative dates

List several uses of GPS that are important for geomorphologists

location determination, placed on benchmarks can measure movement of certain objects (i.e. global movement)

Explain the 2 primary uses of cosmogenic nuclides in geomorphology

measurements of stable and reactive isotopes formed within mineral crystal lattices to estimate cosmic ray exposure of rock outcrops and sediments

How is most radiocarbon (14C) produced?

most radiocarbon is produced in the atm by the interaction of cosmic ray neutrons with nitrogen

What is the most important assumption underlying luminescence dating methods?

overestimates of age because on incomplete bleaching

Where and over what time frame is radiocarbon most useful as a dating method

practical limit: 50,000 yrs

Explain what proxy records are and give an example o how they are used in geomorphology

proxy records are archived data, they cannot be interpreted directly as changes in climate or surface characteristics- can be interpreted through transfer functions

List 4 ways to measure rates of geomorphic processes

sediment generation/yield, landscape change t outcrop and hillslope scales, landscape changes at basin scales, thermochronometry, isotopic methods

Describe several field surveying techniques

stadia rod/level, manual optical instruments, digital total stations, GPS

Explain how the shape of landforms relates to their age

surface processes can change landforms in predictable ways. i.e. a smoother mountain may signify an older mountain as it has had more time to erode or the steepness of a fault scrap.

How does thermochronology work and why is it important to geomorphology

thermochronology is the radiometric dating technique that allows geologists to measure erosion and rock uplift over time of millions to tens of millions of years. The accumulation of stable noble gas isotopes as well as development of fission tracks in certain uranium bearing rock and minerals both provide time/temp histories of rocks. Assume noble gases and damage tracks begin to be retained in minerals when they cool below mineral-specific range in closure temperature and thus at a specific depth below the surface

How does a calibrated relative dating method work

uses observations of time-dependent geomorphic processes occurring on surfaces or deposits of known age to add timing information to relative dating techniques.