Passage:
In 1821, Swiss engineer Ignaz Venetz presented a paper asserting that alpine glaciers had once extended far beyond their current boundaries, citing the widespread distribution of massive, polished rocks known as erratic boulders across the Swiss plain. While contemporary naturalists largely attributed the movement of these boulders to catastrophic ancient deluges, Venetz argued that only slow-moving ice sheets possessed sufficient density to transport such immense stone masses without pulverizing them. To support his claim, Venetz pointed to distinct striations—parallel linear grooves carved into bedrock—which he observed exclusively beneath active glaciers and along valley walls where erratic boulders were concentrated. Although his hypothesis was initially dismissed by the scientific establishment as overly speculative, it eventually provided the empirical foundation for Louis Agassiz’s comprehensive theory of a global Ice Age published two decades later.
According to the passage, which of the following specifies the primary physical reason Venetz gave for why glaciers, rather than water deluges, relocated erratic boulders?
- Ice sheets possessed adequate structural density to convey massive stones without shattering them.Cevap
- BGlaciers moved at rapid speeds capable of incising parallel grooves directly into valley bedrock.
- CGlaciers deposited unique mineral trace signatures along valley walls as they expanded across the plain.
- DIce sheets were observed expanding across the Swiss plain by contemporary naturalists during the early nineteenth century.
- ECatastrophic water deluges lacked the velocity required to deposit boulders along elevated valley walls.