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Zorluk: Çok zorExplicit Causal Relationships

During the transition from the Pleistocene to the Holocene epoch, the sudden return to glacial conditions known as the Younger Dryas was triggered by a complex interplay of hydro-glacial and oceanic mechanisms. As the Laurentide Ice Sheet rapidly retreated due to increasing global temperatures, vast quantities of fresh meltwater accumulated in proglacial Lake Agassiz. The catastrophic breaching of the lake's eastern ice dam redirected this massive freshwater pulse from the Mississippi River drainage system into the North Atlantic Ocean. Because freshwater is significantly less dense than saltwater, this influx stratified the surface waters of the North Atlantic, fundamentally disrupting the thermohaline circulation—the 'global ocean conveyor belt' driven by the sinking of cold, highly saline water. The resultant weakening of the Atlantic meridional overturning circulation drastically reduced the northward transport of equatorial heat. Consequently, despite the broader planetary warming trend, atmospheric temperatures in the Northern Hemisphere plummeted, initiating the millennium-long cooling phase of the Younger Dryas.

According to the passage, which one of the following explicitly caused the stratification of the surface waters in the North Atlantic?

  1. The introduction of a massive volume of freshwater that possesses a lower density than saltwaterCevap
  2. B
    The fundamental disruption of the global ocean conveyor belt driven by sinking cold water
  3. C
    The rapid retreat of the Laurentide Ice Sheet triggered by an overarching planetary warming trend
  4. D
    The catastrophic accumulation of glacial meltwater within the Mississippi River drainage system
  5. E
    The melting of northern polar sea ice resulting from rapidly increasing global temperatures

Cevap

The correct answer identifies the introduction of a massive volume of freshwater that possesses a lower density than saltwater.
The passage explicitly states the causal mechanism for the stratification: 'Because freshwater is significantly less dense than saltwater, this influx stratified the surface waters of the North Atlantic...' The correct answer perfectly paraphrases this dynamic, noting that it was the introduction of the lower-density freshwater that caused the stratification.

Adım Adım Çözüm

1
Analyze the question stem to identify the specific event in the causal chain being asked about.
The target event is 'the stratification of the surface waters in the North Atlantic.'
Focusing on the exact event prevents confusing causes with effects or selecting a distal cause instead of the proximate cause.
2
Scan the passage for the mention of stratification and identify the immediate preceding cause linked by explicit causal language.
The text states: 'Because freshwater is significantly less dense than saltwater, this influx stratified the surface waters...'
The word 'Because' and the phrase 'this influx stratified' explicitly establish the direct cause-and-effect relationship.
3
Evaluate the options to find the one that accurately paraphrases this specific mechanism without introducing errors or reversing the chain.
The correct option correctly attributes the stratification to the influx of lower-density freshwater.
This matches the explicit textual evidence while avoiding familiar wording traps that describe upstream causes or downstream effects.

Anahtar Kavram

Identifying precise, proximate causes within a complex, multi-step causal chain.
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Konular

Explicit Causal Relationships

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