Scientists have found evidence for ice ages by studying
a. subduction zones.
b. volcanoes.
c. fault lines.
d. glaciers.

Which of the layers of the earth has the following three characteristics? i. it is made of molten rock. ii. it has currents that are constantly moving. iii. earth’s plates float on top of its currents.

Canada must balance the economic opportunities offered by its natural resources with the need to maintain links to the united states maintain high tariffs preserve the environment protect its borders

Afarmer who is grown corn for the past five years notices in the sixth year that the his harvest is significantly smaller, despite an increase in labor on the farm. the following year, the harvest continue to decline. which of the following explanations most plausibly accounts for the reduction in corn yield? a) soil degradation b) desalinization c) better irrigationd) terracing