Chalk is used to write on blackboard because

The covers all of earth like a thin shell,but it is not a solid sheet of material.it is broken up into several large sections and many smaller ones. fill in the blank.

Weathering is an example of an external force of change. question 2 options: true false

The oldest rocks in the south atlantic ocean, immediately adjacent to the african and south american continental shelves, are 120,000,000 years old (time). calculate the average rate of seafloorspreading for the south atlantic ocean over its entire existence (hint: use formula: velocity = distance/time): /yr (velocity). now convert that to: cm/yr: