Need these by 3: ! science unit 5-6 test: sculpting earth's !
15. give one example of an environmental problem associated with groundwater and explain the impact it could have on people. *
4 points

4 sentences
16. describe how a stream changes from its headwaters to its source. include changes in its size and shape, gradient, velocity and discharge. *
4 points

4 sentences
17. how do caverns form? what type of rock are caverns most commonly formed from and why? *

15. Groundwater is one of our most important natural resources. It provides us with much of the water that we use for drinking water, household uses, crop irrigation, and many other things. In fact, over 1/3 of Earth's population relies on groundwater for its needs, including 99% of the rural population in the U.S.

16. I dont know this one 

17. One type of cavern, known as solution caverns, are formed when large portions of limestone beneath the ground disintegrate and dissolve through the action of underground water. Solutional caves are the most frequently occurring caves and such caves form in rock that is soluble, such as limestone, but can also form in other rocks, including chalk,dolomite, marble, salt, and gypsum.

This is a time line from 685 to 978