Earth Science Flashcards
What law states that in undisturbed sedimentary rocks, each layer is younger than the layer below it and older than the layer above it
Law of Superposition
A reliable way to tell the Earth’s age
Radioactive Dating
Describe the precambrian era (3)
- algae, sponges, worms
- too primitive to leave any fossils
- most rocks are igneous/ metamorphic
Describe paleozoic era (5)
- ancient life
- most fossils were found in layers of sedimentary rocks
- Devonian period
- appearance of reptiles
- land climate changed
Describe Devonian period(2)
- amphibians: first animal to succeed in adapting itself to breathe air
- land plants began to develop
Describe Mesozoic Era (2)
- formation of several continents
- dinosaurs
Describe Cenezoic Era (4)
- recent life
- volcanic activity
- warm blooded animals
- Northern hemisphere was covered in glaciers, which has signaled the start of Ice age
What are warm blooded animals?
Their temp does not change regardless of their surroundings (birds and mammals)
4 layers of earth
Crust, mantle, inner core, outer core
This is the thin outermost layer of the earth where all life on earth exists
Crust
Describe the outer core of the earth (2)
- liquid iron and nickel
- the intense heat makes the iron and nickel molten as a hot liquid
Describe the inner core of the earth
- Iron and nickel
- very dense due to intense pressure
What is an igneous rock? (2)
- when lava is cooled, it turns into igneous rocks
- obsidian
When magma cools quickly, crystals do not form and the minerals stay mixed in a glass-like solid
Obsidian
What is a sedimentary rock? (2)
- from deposits of the ocean which are made of travels, sand, plant and animal matter
- majority have a banded appearance due to differences in color, grain, etc
