Which is not a factor in a fossil organism being useful as an index fossil? a. it must be limited to a short span of geologic time

b. it must be widespread geographically

c. it must have lived through a long span of time

d. it must be abundant

What is the theme of "the story of the fisherman"?

Which statement explains what upwelling causes? a. upwelling causes tides to rise and fall. b. upwelling causes changes in the direction of currents. c. upwelling causes nutrients, minerals, and tiny organisms to rise. d. upwelling causes currents in the pacific ocean to change direction. i think the answer is c.

The first atomic explosion was detonated in the desert north of alamogordo, new mexico, on july 16, 1945. what percentage of the strontium-90 ( yr) originally produced by that explosion still remains as of july 16, 2016?