Modern Geoscience: Scaling and representativeness

Question 1

when did systematic aerial photography begin and by who?

Answer 1

developed for military purposes in WW1, first practiced by the french photographer and balloonist Nadar in 1858 over Paris.

Question 2

when was the optical microscope invented and by who?

Answer 2

Hans Lippershey (1595), limited the light wavelength to 200nm

Question 3

scanning electron microscopy was fully developed by …. when?

Answer 3

Charles Oatley (1965), increases resolution to 5nm but requires vacuum and coating of specimen.

Question 4

atomic force microscopy was invented by … when?

Answer 4

1986 by Binnig and Rohrer (physics nobel prize)

requires no sample preparation,resolution to <1nm, can examine human hair

Question 5

whats random sampling?

Answer 5

• Least biased

- Can be done using random number tables

Question 6

advantages and disadvantages of random sampling…

Answer 6

• Advantages
  Can be used with large sample
  Avoids bias
• Disadvantages
  Could lead to poor representation of overall sample
  Might come up against practical constraints of access or time

Question 7

whats systematic sampling?

Answer 7

using regular pattern of samples (eg - transects)

Question 8

advantages and disadvantages of systematic sampling….

Answer 8

• Advantages
  Straightforward to design
  Guaranteed good coverage
  Results easy to analyse
• Disadvantages
  More biased – some points have no chance of being selected
  May over- or under represent a particular pattern type

Question 9

whats stratified sampling?

Answer 9

The population/area is divided into known groups, and each group sampled using a systematic approach.
The number sampled in each group should be in proportion to its known size in the parent population.

Question 10

advantages and disadvantages of stratified sampling …

Answer 10

• Advantages
  Can be used with random or systematic sampling
  Generates results more representative of the overall population
  Adaptable to many situations
  Allows correlations and comparisons between subsets
• Disadvantage
  Proportions of subsets must be known

Question 11

whats space for time substitution?

Answer 11

Allows different stages/ages of processes or development to be compared directly
Assumes processes in the past acted similarly to current processes (Uniformitarianism).
example - Davisian cycle of erosion - assumption is far fetched, has the climate changed over time?