The tide-gauge notebooks
Holding one distinction — what was measured versus what was inferred — across four questions.
Passage
For sixty years, keepers at the Fenwick light recorded the height of each high tide in bound notebooks. The entries are terse: a date, a time, a number in feet and inches, occasionally a word about weather. Nothing in them was intended as science; the keepers were logging conditions for the boats that used the channel.
When the notebooks were digitised in 2019, researchers found that the sixty-year record showed a slow rise in mean high-water height. The keepers had not been trying to measure sea level, and none of the entries mentions it. The rise is visible only when the individual readings are averaged over years, which no keeper ever did.
Answers in order, explanations withheld, and a report on where the chain broke.
- 24.1Central ideas and detailsStandard
Which choice best states the main point of the text?
- AA record kept for one purpose turned out to answer a question nobody was asking when it was made.
- BThe keepers at the Fenwick light were conducting an early sea-level study.
- CDigitising historical records is the most reliable way to measure sea level.
- DThe notebooks were poorly kept and their readings cannot be trusted.
Show the answer and reasoningHide the reasoning
A record kept for one purpose turned out to answer a question nobody was asking when it was made.
The text is built on the gap between why the notebooks exist (conditions for boats) and what they later showed (a rise in mean high water). The other choices contradict the explicit statement that nothing was intended as science, or add judgements about reliability and method the text does not make.
- 24.2InferencesStandard
Builds on: The distinction in question 1 between the purpose of the record and what it turned out to show.
Which choice is best supported by the text?
- AA measurement can carry information its recorder did not know it held.
- BThe keepers suspected sea level was rising but lacked the means to prove it.
- CAveraging obscures detail that individual readings preserve.
- DRecords kept without a scientific purpose are usually more accurate.
Show the answer and reasoningHide the reasoning
A measurement can carry information its recorder did not know it held.
The keepers recorded heights without any sea-level question in mind, and the rise emerged from those same numbers. That is precisely information carried but not known. The text says nothing about the keepers suspecting anything, and it credits averaging with revealing the pattern rather than obscuring it.
- 24.3Command of evidenceChallenge
Builds on: The reading in question 2 that the value of the record lies in the numbers themselves.
A researcher argues that the Fenwick record is usable evidence of local sea-level change. Which finding would most weaken that argument?
- AThe gauge the keepers read from was reset to a new zero point several times without being logged.
- BThe keepers occasionally noted weather alongside the height.
- CThe notebooks were not digitised until 2019.
- DNo keeper ever averaged the readings.
Show the answer and reasoningHide the reasoning
The gauge the keepers read from was reset to a new zero point several times without being logged.
A rise measured against a shifting and unrecorded baseline is not a rise in sea level; it could be an artefact of the resets. The other three are all stated or implied in the text already and did not stop the pattern appearing, so none of them can weaken the argument.
- 24.4Text structure and purposeStandard
The final sentence of the text mainly serves to
- Aexplain why the pattern went unnoticed for sixty years.
- Bcriticise the keepers for failing to analyse their own data.
- Cargue that averaging should be applied to all historical records.
- Dintroduce a disagreement among the researchers.
Show the answer and reasoningHide the reasoning
explain why the pattern went unnoticed for sixty years.
The sentence says the rise is visible only when readings are averaged, and that no keeper did that. Put together, those two facts account for the delay. Nothing in the sentence blames anyone or generalises to other records.