Read the passage below. The first sentence contains a nonessential parenthetical phrase that is introduced by a dash. What punctuation mark should be placed in the blank to maintain punctuation consistency and correctly set off this phrase?
Answer:In 1974, a team of glaciologists embarked on a pioneering expedition to retrieve ice cores from the Quelccaya Ice Cap—the largest ice mass in the tropics【—】hoping to reconstruct a detailed history of the region's climate. The ancient ice contains dust particles, volcanic ash, and chemical signatures that reveal past weather patterns. By analyzing these layers, the scientists successfully created a year-by-year climate record spanning over fifteen centuries.
Answer
A dash (—)
The sentence contains a nonessential parenthetical phrase, 'the largest ice mass in the tropics,' which describes the 'Quelccaya Ice Cap.' Under standard conventions, nonessential phrases must be enclosed by matching punctuation marks (either a pair of commas, a pair of parentheses, or a pair of dashes). Because the phrase begins with a dash after 'Quelccaya Ice Cap,' it must end with a matching dash before 'hoping' to ensure consistency and grammatical correctness.
Step-by-Step Solution
Key Concept
Punctuation consistency with parenthetical elements (dashes)