Scientists studying Mars long thought the history of its crust was relatively simple. One reason for this is that geologic...
GMAT Information and Ideas : (Ideas) Questions
Scientists studying Mars long thought the history of its crust was relatively simple. One reason for this is that geologic and climate data collected by a spacecraft showed that the crust was largely composed of basalt, likely as a result of intense volcanic activity that brought about a magma ocean, which then cooled to form the planet's surface. A study led by Valerie Payré focused on additional information—further analysis of data collected by the spacecraft and infrared wavelengths detected from Mars's surface—that revealed the presence of surprisingly high concentrations of silica in certain regions on Mars. Since a planetary surface that formed in a mostly basaltic environment would be unlikely to contain large amounts of silica, Payré concluded that ______
Which choice most logically completes the text?
the information about silica concentrations collected by the spacecraft is likely more reliable than the silica information gleaned from infrared wavelengths detected from Mars's surface.
high silica concentrations on Mars likely formed from a different process than that which formed the crusts of other planets.
having a clearer understanding of the composition of Mars's crust and the processes by which it formed will provide more insight into how Earth's crust formed.
Mars's crust likely formed as a result of other major geological events in addition to the cooling of a magma ocean.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| Scientists studying Mars long thought the history of its crust was relatively simple. |
|
| One reason for this is that geologic and climate data collected by a spacecraft showed that the crust was largely composed of basalt, likely as a result of intense volcanic activity that brought about a magma ocean, which then cooled to form the planet's surface. |
|
| A study led by Valerie Payré focused on additional information—further analysis of data collected by the spacecraft and infrared wavelengths detected from Mars's surface—that revealed the presence of surprisingly high concentrations of silica in certain regions on Mars. |
|
| Since a planetary surface that formed in a mostly basaltic environment would be unlikely to contain large amounts of silica, Payré concluded that _______ |
|
Provide Passage Architecture & Core Elements
Main Point: New evidence of high silica concentrations on Mars challenges the original simple explanation of how the planet's crust formed, suggesting a more complex formation process.
Argument Flow: The passage moves from an established simple theory about Mars's crust formation (supported by basalt evidence) to new contradictory evidence (high silica concentrations) that logically demands a revised, more complex explanation of the formation process.
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 passage sets up a clear logical problem: if Mars's crust formed simply from a cooling magma ocean (creating a basaltic environment), we wouldn't expect to find high silica concentrations
- Payré's study found exactly that - high silica in certain regions
- This contradiction means our original simple explanation is incomplete
- The right answer should conclude that Mars's crust formation involved additional geological events or processes beyond the simple cooling magma ocean explanation
the information about silica concentrations collected by the spacecraft is likely more reliable than the silica information gleaned from infrared wavelengths detected from Mars's surface.
✗ Incorrect
- This focuses on comparing the reliability of different data collection methods, but the passage doesn't question the reliability of either data source
high silica concentrations on Mars likely formed from a different process than that which formed the crusts of other planets.
✗ Incorrect
- This compares Mars's formation process to other planets, but the passage makes no mention of other planets
having a clearer understanding of the composition of Mars's crust and the processes by which it formed will provide more insight into how Earth's crust formed.
✗ Incorrect
- This shifts focus to understanding Earth's crust formation, but the passage is entirely about Mars
Mars's crust likely formed as a result of other major geological events in addition to the cooling of a magma ocean.
✓ Correct
- This directly addresses the logical problem: if basaltic environments don't typically have high silica, but Mars does have high silica, then other geological events must have occurred beyond the simple cooling magma ocean explanation