Answer:
The International Date Line provides a standard means of making the needed readjustment: travelers moving eastward across the line set their calendars back one day, and those traveling westward set theirs a day ahead.
That statement is true.
When making the world map for example, many advancement were made after we received the idea that the Earth is Round.
So both geographical movement expression and ideas are not something that could be separated.
I believe the answer is earthquakes.
