7th Grade Science Rocks Name: _______________________

7^th Grade Science Rocks Name: ________________________

Matching:

A. Igneous

B. Metamorphic

C. Sedimentary

D. Hydrothermal

E. Microcrystalline

F. Tufa

G. Pumice

H. Magma

I. Lava

1. ___ Light-colored compacted volcanic ash, a very soft stone.

2. ___ Molten rock found far beneath the earth’s surface.

3. ___ Rocks subjected to so much heat and pressure they change form.

4. ___ Process of hot, pressurized water dissolving minerals.

5. ___ Light, hard, abrasive volcanic rock expanded by volcanic gasses.

6. ___ Rocks that have formed from molten material.

7. ___ Jasper and agates are made of very tiny quartz crystals, too small to easily see.

8. ___ Molten rock after it comes to the surface, usually from a volcano.

9. ___ Many small, weathered particles collected and glued together into a new rock.

10. The Hawaiian Islands are composed mainly of which rock?

(a) Basalt (b) Pumice (c) Granite (d) Marble

11. Which is NOT an example of physical weathering?

(a) cracking by freezing (b) action of acid rain

12. Marble is a type of ____ rock.

(a) Sedimentary (b) Igneous (c) Metamorphic

13. Sandstone and limestone will be ___ rocks.

(a) Sedimentary (b) Igneous (c) Metamorphic

14. Granite is always a ___ rock.

(a) Sedimentary (b) Igneous (c) Metamorphic

15. The process of rapid, violent change is called:

(a) uniformitarianism (b) catastrophism

16. Chemical weathering happens due to:

(a) Organic acids in plant roots (b) Acids dissolved in rains

17. Describe our lab experiment:

Weathering of Human Artifacts

Since early geologic time, the atmosphere has interacted with the Earth's exposed crust though a process known as weathering. Weathering takes place through a combination of both mechanical and chemical means. We have all experienced the results of weathering first hand. Any visit to an old cemetery find us peering at the blurred inscriptions on old marble tombstones. These inscriptions were once perfectly legible, but with the passage of time, the small fractures and cracks in the rock have made it vulnerable to attack by aqueous solutions. A dramatic example of weathering can be seen in the images of the same 3000 year old Egyptian obelisk just before relocation to damp New York and 100 years after accelerated weathering in New York. Weathering rates are obviously a strong function of climate!

Many of the original volcanic gases (e.g., carbon dioxide, sulphur-bearing gases, etc.) were able to dissolve in water and produce acids. The acids, in turn, reacted with surface minerals. Later, oxygen in the atmosphere reacted with the exposed reduced materials, making the red beds of stone. Since the advent of land plants, soil and surface minerals have been exposed to relatively high concentrations of carbon dioxide maintained in soil pores as a result of decomposition and the metabolic activities of roots. The reaction of carbon dioxide with water in the soil produces carbonic acid, which determines the rate of rock weathering in most ecosystems.

Much of the rock art heritage in the Drakensberg and adjacent mountains of southern Africa is being lost through natural rock weathering processes, the decay of pigments and through vandalism by humans. The deterioration of San paintings in southern Africa was noted as early as the late Eighteenth Century in the south-western parts of the sub-continent . The deterioration of rock art was only recognised by earth scientists in the context of providing an estimation of the rate of relative weathering rates. Despite an acknowledgement of the negative impact of rock weathering processes on San paintings, little has been achieved with regard to the preservation of indigenous rock art in southern Africa.

18. What is this article about?

19. The older man-made items discussed here come from which continent?

(a) North America (b) South America (c) Africa (d) Asia

20. List three mechanisms by which a rock can be weathered:

BONUS: How would you protect these artifacts from weathering?