The term "remote sensing" refers to the techniques of measurement and

Question

The term "remote sensing" refers to the techniques of measurement and interpretation of phenomena from a distance. Prior to the mid-1960's the interpretation of film images was the primary means for remote sensing of the Earth's geologic features. With the development of the optomechanical scanner, scientists began to construct digital multispectral images using data beyond the sensitivity range of visible light photography. These images are constructed by mechanically aligning pictorial representations of such phenomena as the reflection of light waves outside the visible spectrum, the refraction of radio waves, and the daily changes in temperature in areas on the Earth's surface. Digital multispectral imaging has now become the basic tool in geologic remote sensing from satellites.

The advantage of digital over photographic imaging is evident: the resulting numerical data are precisely known, and digital data are not subject to the vagaries of difficult to control chemical processing. With digital processing, it is possible to combine a large number of spectral images. The acquisition of the first multispectral digital data set from the multispectral scanner (MSS) aboard the satellite Landsat in 1972 consequently attracted the attention of the entire geologic community. Landsat MSS data are now being applied to a variety of geologic problems that are difficult to solve by  conventional methods  alone. These include specific problems in mineral and energy resource exploration and the charting of glaciers and shallow seas.

A more fundamental application of remote sensing is to augment conventional methods for geologic mapping of large areas. Regional maps present compositional, structural, and chronological information for reconstructing geologic evolution. Such reconstructions have important practical applications because the conditions under which rock units and other structural features are formed influence the occurrence of ore and petroleum deposits and affect the thickness and integrity of the geologic media in which the deposits are found.

Geologic maps incorporate a large, varied body of specific field and laboratory measurements, but the maps must be  interpretative  because field measurements are always limited by rock exposure, accessibility and labor resources. With remote-sensing techniques it is possible to obtain much geologic information more efficiently than it can be obtained on the ground. These techniques also facilitate overall interpretation. Since detailed geologic mapping is generally conducted in small areas, the continuity of regional features that have intermittent and variable expressions is often not recognized, but in the comprehensive views of Landsat images these continuities are apparent. However, some critical information cannot be obtained through remote sensing, and several characteristics of the Landsat MSS impose limitations on the acquisition of diagnostic data. Some of these limitations can be overcome by designing satellite systems specifically for geologic purposes; but, to be most effective, remote-sensing data must still be combined with data from field surveys and laboratory tests, the techniques of the earlier twentieth century.  
 1 
 C 
 Q1. By using the word “interpretative” in line 40, the author is indicating which of the following?

(A) Some maps are based more on data from aerial photography than on data from field operations.
(B) Some maps are based almost exclusively on laboratory measurements.
(C) Some maps are based on incomplete data from field observations.
(D) Some maps show only large geologic features.
(E) Some maps can be three-dimensional.

2 
 D 
 Q2. With which of the following statements about geologic mapping would the author be most likely to agree?

(A) Geologic mapping is basically an art and not a science.
(B) Geologic mapping has not changed significantly since the early 1960’s.
(C) Geologic mapping will have limited practical applications until remote-sensing systems are perfected.
(D) A developmental milestone in geologic mapping was reached in 1972.
(E) Without the present variety of remote-sensing techniques, geologic mapping could not be done.

3 
 C 
 Q3. According to the passage, measurements of which of the following can be provided by the optomechanical scanner but not by visible-light photography?

(A) The amount of visible light reflected from oceans
(B) The density of foliage in remote areas on the Earth’s surface
(C) Daily temperature changes of areas on the Earth’s surface
(D) The degree of radioactivity emitted by exposed rocks on the Earth’s surface
(E) Atmospheric conditions over large landmasses

4 
 C 
 Q4. It can be inferred from the passage that a major disadvantage of photographic imaging in geologic mapping is that such photography

(A) cannot be used at night
(B) cannot focus on the details of a geologic area
(C) must be chemically processed
(D) is always enhanced by digital reconstruction
(E) cannot reflect changes over extended periods of time

5 
 B 
 Q5. It can be inferred from the passage that Landsat images differ from conventional geologic maps in that Landsat images

(A) reveal the exact size of petroleum deposits and ore deposits
(B) indicate the continuity of features that might not otherwise be interpreted as continuous
(C) predict the movements of glaciers
(D) provide highly accurate data about the occurrence of mineral deposits
(E) reveal the integrity of the media in which petroleum deposits and ore deposits are found

6 
 E 
 Q6. The passage provides information about each of the following topics EXCEPT:

(A) the principal method of geologic remote sensing prior to the mid-1960’s
(B) some of the phenomena measured by digital multi-spectral images in remote sensing
(C) some of the practical uses of regional geologic maps
(D) the kinds of problems that are difficult to solve solely through conventional methods of geologic mapping
(E) the specific limitations of the Landsat multi-spectral scanner

7 
 A 
 Q7. The passage suggests which of the following about the “conventional methods” mentioned in line 29?

(A) They consist primarily of field surveys and laboratory measurements.
(B) They are not useful in providing information necessary for reconstructing geologic evolution.
(C) They have rarely been used by geologists since 1972.
(D) They are used primarily to gather compositional information about geologic features.
(E) They are limited primarily because of difficulties involved in interpreting film images.

mafuz · Answer

Thanks  homersimpsons

Such an amazing reading. Specially liked Q4 and Q6. I am a bit lost in Q7. Can anyone please explain how to connect `conventional method` with `A`

TanmayT · Answer

Hi! Can somebody please provide the OEs and the individual difficulty levels of all the questions?

Thanks!

bM22 · Answer

Hi  mafuz ,

A for Question 7 can be inferred from:
"A more fundamental application of remote sensing is to augment conventional methods for geologic mapping of large areas." and "Geologic maps incorporate a large, varied body of specific field and laboratory measurements,".

Implication being: A basic application of remote sensing would be increase the use conventional methods for mapping of large areas, now this Geologic mapping involves mostly field and laboratory measurements.

Hope This Helps.
Thanks.

RiteshGadave · Answer

In Q6 Due to following sentence i was convinced that limitations of the Landsat multi-spectral scanner is stated.
(*Landsat MSS impose limitations on the acquisition of diagnostic data. Some of these limitations can be overcome by designing satellite systems specifically for geologic purposes.*) And moreover it is written that prior to the mid-1960's.... interpretation of film images was the primary means for remote sensing ....but here they have not mentioned the exact  principal  method for remote sensing...they have only stated that film images were used...So i selected option A over E.......Please help me in this....

Also please explain Q2 ...i have no clue about it....

mafuz · Answer

Thanks a lot bm2201 The explanation is indeed helpful.

mafuz · Answer

Hi  RiteshGadave 
Q2: I applied POE and a bit reading from the passage. Take a look at... With digital processing, it  is possible  to combine a large number of spectral images. The acquisition of the first multispectral digital data set from the multispectral scanner (MSS) aboard the satellite Landsat in 1972 consequently  attracted the attention of the entire geologic community .

In the above text 1972 is important because in this year something happened (Landsat) that helped to overcome an `impossibility` and consequently attract   Entire   G. community. I paused `D` because 1972 discovery is important.

Now POE. 
(A) art vs. science. Is it really a discussion point in the passage. No!
(B) G. mapping has not changed since 1960. Not true!
(C) `practical`...`perfected`. It seems not relevant according to the passage
(E) ` could not be done`. Not true!

So, I should stand on D and move on...

Saasingh · Answer

Can someone explain how B is right on Q5?

Only accuracy and precision of Digital data is talked about. I don't see how continuity can be inferred. I re-read that para again and again and still cannot figure it out.

bM22 · Answer

Hi  Saasingh ,

Option B for Question 5 can be inferred from the lines:
"Since detailed geologic mapping is generally conducted in small areas, the continuity of regional features that have intermittent and variable expressions is often not recognized, but in the comprehensive views of Landsat images these continuities are apparent."

Hope This Helps.
Thanks.

Jks3000 · Answer

Sajjad1994   bm2201  Please explain Q3. I think all among options b,c,d cannot be represented by visible-light photography?!!

Sajjad1994 · Answer

Read the lines:

With the development of the optomechanical scanner, scientists began to construct digital multispectral images using data  beyond the  sensitivity  range of visible light photography.  These images are constructed by mechanically aligning pictorial representations of such phenomena as the  reflection of light waves outside the visible spectrum,  the refraction of  radio waves , and the   daily changes in temperature   in areas on the Earth's surface.

(A) The amount of visible light reflected from oceans

(B) The density of foliage in remote areas on the  Earth’s surface

(C)  Daily temperature changes  of areas on the Earth’s surface

(D) The degree of radioactivity emitted by  exposed rocks  on the Earth’s surface

(E)  Atmospheric conditions  over large landmasses

Only C stands

VerbalBot · Answer

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The term "remote sensing" refers to the techniques of measurement and

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The term "remote sensing" refers to the techniques of measurement and

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