Examkin

Question

Difficulty: MediumReading Comprehension: Passage-Based Word in Context Analysis

In geomorphology, the evolution of bedrock rivers is often governed by knickpoints—abrupt slope alterations in a river profile usually caused by tectonic uplift or base-level lowering. While early models treated knickpoints as static boundaries marking distinct erosional regimes, recent hydrodynamic simulations demonstrate that knickpoints actively propagate upstream, consuming the relict landscape above them. As the slope steepens, the resulting increase in shear stress enhances bedrock incision, driving a continuous wave of retreat. Far from merely transmitting a passive signal of environmental perturbation, this migratory behavior reflects a dynamic readjustment of channel geometry. Consequently, geomorphologists must view knickpoint migration not as an ephemeral anomaly, but as the primary mechanism through which drainage basins continuously sculpt landscape topographies over geological timescales.

Based on the passage above, which of the following best captures the meaning of the word propagate as it is used by the author?

  1. A
    reproduce biologically or multiply
  2. migrate or travel physically upstreamAnswer
  3. C
    induce or trigger tectonic uplift
  4. D
    radiate seismic waves through bedrock
  5. E
    dissipate completely into sediment

Answer

The term 'propagate' as used in the passage means to migrate or travel physically upstream along the river profile.
The correct answer is the option stating 'migrate or travel physically upstream'. The passage explicitly pairs 'propagate' with the direction 'upstream' and refers back to this process as 'this migratory behavior' and 'knickpoint migration', establishing that the word refers to spatial movement along the riverbed.

Step-by-Step Solution

1
Analyze the immediate sentence context containing the target word.
The text states that 'knickpoints actively propagate upstream, consuming the relict landscape above them.'
Word meaning in reading comprehension is dictated by surrounding modifiers and parallel descriptions.
2
Examine surrounding structural clues and restatements.
The subsequent sentences refer to 'a continuous wave of retreat', 'this migratory behavior', and 'knickpoint migration'.
The author explicitly rephrases the action of propagating as 'migratory behavior' and 'migration'.
3
Evaluate option choices against the contextual evidence.
The option stating 'migrate or travel physically upstream' matches the author's description of physical displacement along the river channel.
Only this definition aligns with the spatial movement described throughout the passage.

Key Concept

Passage-Based Word in Context Analysis
Estimated Time:1m 30s
Rate this question

Topics

Reading Comprehension: Passage-Based Word in Context Analysis

More questions from this topic