:
approximately what portion of north america is covered by forest?
a).1/4
b).1/3
c).1/2
d).3/5

Which of the layers of the earth has the following three characteristics? i. it is a solid outer layer. ii. it is between 3 and 30 miles thick. iii. it is separated into plates. a. the outer core b. the inner core c. the mantle d. the crust