I recently read an article where it said that during the gold standard, right before world war 1, 1 GBP went from equaling \$4.87 to soaring up to \$6.75 . My understanding always was that Forex rates couldn't fluctuate during the gold standard since the both currencies were tied to gold. So my main question is: could Foreign exchange rates fluctuate during the gold standard? And what usually would cause these foreign rates to fluctuate relative to one another under a gold-standard system??
Here is the document: https://fraser.stlouisfed.org/files/docs/meltzer/craint89.pdf
It says "Late in July, as foreigners began liquidating their holdings of U.S securities and as U.S. debtors scrambled to meet their obligations to pay in sterling, the dollar-pound exchange rate soared as high as \$6.75, far above the parity of \$4.8665"