Final answer:
The Appalachian Mountains provided a natural barrier against the growth of British colonies in North America.
Step-by-step explanation:
The physical feature that provided a natural barrier against the growth of British colonies in North America was the Appalachian Mountains.
The colonists with frontiers abutting the Appalachian Mountains expected these lands to be opened for settlement, while the British viewed the question of the western lands differently. The mountains acted as a geographical boundary that limited westward expansion and made it difficult for the British colonies to expand further.