Data collected by the Mars rover Curiosity at the Gale Crater's Murray Formation are suggestive of hydrological deposition of sediment...
GMAT Information and Ideas : (Ideas) Questions
Data collected by the Mars rover Curiosity at the Gale Crater's Murray Formation are suggestive of hydrological deposition of sediment in the distant past. To characterize the nature of the depositional environment, Frances Rivera-Hernández et al. analyzed the grain size of Murray Formation sediment, finding that although there are intervals of coarse grains, most of the sediment consists of fine grains that show signs of cracking due to episodic desiccation. Rivera-Hernández et al. concluded that the coarse grains are sandstone, which tends to be deposited by flowing water, whereas the fine grains are mudstone, which is slowly deposited by settling out of suspension in low-flow water, leading the researchers to posit that ______
Which choice most logically completes the text?
although the area of the Murray Formation experienced a prolonged period of dryness that prevented a lake from forming, water flowing from a distant source was present.
a lake existed at the Murray Formation for a prolonged period, though the lake occasionally experienced drying and there were periods in which one or more streams were present.
one or more streams existed at the Murray Formation for an extended period until being replaced by a lake that persisted for only a brief period before permanently drying.
a stream-fed lake was present at the Murray Formation for an extended period, and although the streams experienced occasional drying, the lake did not.
Step 1: Decode and Map the Passage
Part A: Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Data collected by the Mars rover Curiosity at the Gale Crater's Murray Formation are suggestive of hydrological deposition of sediment in the distant past." |
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| "To characterize the nature of the depositional environment, Frances Rivera-Hernández et al. analyzed the grain size of Murray Formation sediment" |
|
| "finding that although there are intervals of coarse grains, most of the sediment consists of fine grains that show signs of cracking due to episodic desiccation." |
|
| "Rivera-Hernández et al. concluded that the coarse grains are sandstone, which tends to be deposited by flowing water" |
|
| "whereas the fine grains are mudstone, which is slowly deposited by settling out of suspension in low-flow water" |
|
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- The evidence shows two key things: fine grains (mudstone from still water) that have cracking from episodic desiccation, and coarse grains (sandstone from flowing water)
- The fine grains dominate, suggesting still water was the primary condition, but the cracking shows this still water environment occasionally dried out
- The presence of coarse grains indicates flowing water was also present at times
although the area of the Murray Formation experienced a prolonged period of dryness that prevented a lake from forming, water flowing from a distant source was present.
- Suggests no lake formed, only flowing water from distant sources
- Contradicts the dominant fine grain evidence showing still/low-flow water deposition
a lake existed at the Murray Formation for a prolonged period, though the lake occasionally experienced drying and there were periods in which one or more streams were present.
- Describes a lake existing for a prolonged period (matches dominant fine grains/mudstone)
- Acknowledges occasional drying (matches the cracking from episodic desiccation)
- Includes periods with streams (matches the coarse grains/sandstone evidence)
one or more streams existed at the Murray Formation for an extended period until being replaced by a lake that persisted for only a brief period before permanently drying.
- Suggests streams came first, then a brief lake period
- Contradicts the evidence that fine grains (indicating still water) dominate the formation
a stream-fed lake was present at the Murray Formation for an extended period, and although the streams experienced occasional drying, the lake did not.
- Claims the lake did not dry even though streams did
- Directly contradicts the cracking evidence showing episodic desiccation affected the fine grains