Formation of Rocks

Question 1

Define rock

Answer 1

Any naturally occurring solid mass or aggregate of minerals or mineraloid matter

Question 2

Classification of rock

Answer 2

Igneous, metamorphic, sedimentary

Question 3

Formation of igneous rocks

Answer 3

Is solidified molten material and can be volcanic (extrusive) or plutonic (intrusive)

Question 4

Distinguish between intrusive and extrusive rocks using crystal size

Answer 4

• the most obvious difference is size:
  
  • extrusive rocks cool quickly, they only have time to form very small crystals such as basalt or none at all
  • intrusive rocks grow larger crystals because they take longer to cool

Question 5

Formation of metamorphic rocks

Answer 5

Rocks formed after intense heat or pressure and involve recrystallization

Question 6

Formation of sedimentary rocks

Answer 6

• the weathering and erosion of small particles from other rocks
• the sediments are carried to water bodies and after several layers accumulation, the pressure from above in conjunction with the crystallization of dissolved chemicals in the water result in layers of cemented rock