Final answer:
The term for the misconception that the New World was an unpopulated, unaltered wilderness upon Columbus's arrival is the Pristine myth.
Step-by-step explanation:
The misconception that the New World was a lightly populated, unmodified wilderness when first encountered by Christopher Columbus is known as the Pristine myth. This myth has been debunked by evidence that the Americas were extensively populated by millions of indigenous peoples who extensively altered their surroundings. Accounts and scientific findings emphasize that humans have historically inhabited and modified virtually every part of the globe, and the changes made by indigenous populations have profound and lasting effects on populations and ecosystems.