Question 170·200 Super-Hard SAT Reading Questions·Craft and Structure
Geologists studying a river that crosses a slowly rising ridge determined that the channel predates the uplift. As the rock rose, the river cut downward fast enough to maintain its route, producing steep walls that increasingly restricted lateral migration. This interaction therefore ______ the inherited course, both preserving its position and deepening its expression in the landscape.
Which choice completes the text with the most logical and precise word or phrase?
For a words-in-context question, identify every feature the blank must convey rather than matching only one nearby clue. Then compare the scope of the options: the most precise choice should fit the sentence grammatically and account for all the effects described in the surrounding text.
Hints
Use both parts of the final clause
The best choice must account for the course's preserved position as well as its increased depth.
Consider the geological context
Look for a word that can describe a route becoming harder to change specifically because downward cutting has confined it.
Step-by-step Explanation
Identify the two required meanings
The river maintained its existing route while cutting downward. Its steep walls then restricted its ability to migrate sideways.
Choose the word covering both meanings
“Entrenched” can mean firmly established and, in the context of a river, deeply cut into the surrounding land. It therefore accounts for both the course's persistence and its physical deepening.