Under which circumstances should we try to control the population numbers of pfiesteria?

my teacher would say no s

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.