Three Types of Rocks

Which statement best describes how igneous rocks form?

• By cooling of molten rock from deep within or above the Earth's surface

• By pressing and cementing of layers of sand and shells

• By plants growing into cracks of rocks

• By water dissolving minerals and leaving holes

Igneous rocks are typically:

• Soft and easily broken

• Very hard and resistant to extreme hot temperatures

• Full of visible fossils

• Always light-colored

Which type of rock does not contain any fossils according to the lesson?

• Sedimentary rock

• Metamorphic rock

• Igneous rock

• All rock types

Which pair lists only igneous rock examples shown in the lesson images?

• Basalt and Obsidian

• Sandstone and Shale

• Marble and Slate

• Coal and Limestone

Sedimentary rocks form from:

• Cooling magma

• Heat and pressure changing older rocks

• Sediments like sand, shells, pebbles, and broken pieces that accumulate on Earth's surface

• Crystals growing deep underground only

Which feature helps you identify a sedimentary rock?

• Recognizable layers and may contain fossils

• Metallic shine and magnetic pull

• Sharp crystals in every sample

• Always black color

Which list shows only sedimentary rock examples from the images?

• Breccia, Conglomerate, Sandstone

• Gneiss, Schist, Slate

• Granite, Basalt, Obsidian

• Quartzite, Marble, Phyllite

Metamorphic rocks are formed when other rocks go through metamorphism, which mainly involves:

• Melting and erupting quickly

• Extreme heat and pressure for a long period of time

• Being broken by waves

• Freezing and thawing with water

A common characteristic of metamorphic rocks is that they:

• Have recognizable layers with fossils

• Have shiny crystals and layers of planes that can appear like ribbons

• Always form from lava cooling at the surface

• Are the softest of all rocks

Which set lists only metamorphic rock examples shown in the images?

• Marble, Gneiss, Slate

• Basalt, Diorite, Rhyolite

• Shale, Chalk, Gypsum

• Dacite, Granite, Gabbro