Final answer:
True, the Flint Hills were formed approximately 250 million years ago. They are made primarily of limestone and shale and have been shaped by erosion.
Step-by-step explanation:
True or False: The Flint Hills have been "in the making" for 250 million years. This statement is indeed true. The Flint Hills, located in the eastern part of Kansas and extending into northern Oklahoma, are a region characterized by numerous steep hills and grasslands.
Formed during the Permian Period around 250 million years ago when the area was covered by an inland sea, the Flint Hills are composed majorly of limestone and shale. These materials were deposited over vast periods as sediment at the bottom of the sea, which later hardened into rock.
Through the processes of erosion and weathering, the harder limestone resisted erosion better than the surrounding rock, giving the Flint Hills their distinct appearance.
The discussion about agriculture beginning approximately 45,000 years ago is not directly related to the formation of the Flint Hills but provides context for the timescale of human activities compared to geological processes.
Additionally, the present-day Southeastern United States was one of the world's independent centers for plant domestication, which makes the statement true.