Well if you mean what does the controlled part of a scientific investigation, it is the part of the investigation that will be your control or your base, untouched, original, data and such.
Answer:
According to one estimate, stands of century-old forest now account for only 7% of forest cover in the United States (USDA-FS 2000). Since 1600, 90% of the virgin forests that once covered much of the lower 48 states have been cleared away.
Explanation:
Mount Baker-Snoqualmie National Forest, Washington
The Mount Baker-Snoqualmie forest is located in the Cascade mountain range in Washington state and is home to 644,000 acres of old-growth. Situated around an hour away from the Seattle metropolitan area, this forest is one of the most frequently visited in the country.
The rock must be granite.
