Acraton is a large, stable portion of earth's
lithosphere that makes up part of a continent.
the kaapvaal craton in africa is one of five
ancient cratons left from the precambrian era.
the rock has remained tectonically stable since
its formation 3.6 billion to 2 billion years ago.
what do you think the term "tectonically stable"
means? why do you think this rock formation is
important to understanding the history of earth?
do you think studying ancient rock formations
such as the kaapvaal craton can teach scientists
not only about earth's past but also its future?
why or why not?

The great scientist alfred wegener proposed that continents have moved, while other scientists such as t.c.chamberlin argued against wegener. wegener's ideas eventually won, and are now widely accepted, because: a) wegener's ideas were more beautiful, and so were favored by the intellectual elite.b) wegener's ideas did a better job of predicting the results of new observations and experiments.c) wegener's ideas appealed to dead white european males, whereas chamberlin's didn't.d) wegener's ideas appalled dead white european males, and we all know that in this politically correct era,dead white european males cannot get a fair shake.e) wegener won the nobel prize.

Zac wanted to determine the measure of r and of ? r in the triangle below. to fine the measure of r, zac sets up the problem.42^2 + 24^2 = r 2. determine whether zac set the problem up correctly.

Arow of elements on the periodic table is called an