Science assessment-part 2 Flashcards
(20 cards)
note: sedimentary, igneous and metamorphic rocks all contain minerals
👍🏼
origins and relationships between sedimentary, igneous, and metamorphic rocks
Sedimentary, igneous, and metamorphic rocks are connected through the rock cycle, where igneous rocks form from cooled lava, sedimentary rocks form from layers of sediments, and metamorphic rocks form from changes in other rocks due to heat and pressure.
How do fossils form
Fossils form when a plant or animal dies and gets buried in sedimentary rock layers. The burying helps protect the body. Over time, the soft parts, like skin, rot away, but the hard parts, like bones, stay. Minerals replace the bones, turning them into rock and preserving the shape.
Why in sedimentary layers, is the oldest at the base and the youngest at the top
The oldest layers are at the bottom because new layers keep forming on top of the older ones, this is why the oldest dead remains are at the bottom of the layers.
What are the 3 types of rocks
Igneous - Formed from cooled magma/lava
Sedimentary - Made from layers of compacted sediments
Metamorphic - Created when existing rocks are changed by heat and pressure.
How does the speed of cooling affect the size of crystals in igneous rocks?
Slow cooling igneous rocks tend to have large crystals then those igneous rocks formed through rapid cooling of magma/lava.
What are extrusive and intrusive igneous rocks?
Extrusive igneous rock- forms when lava cools quickly on the surface, like basalt.
Intrusive igneous rock- forms when magma cools slowly underground, like granite.
What type of rocks are formed when mountains are being made and the crust is folding?
Metamorphic rocks
What are ores
Ores are rocks that contain enough valuable minerals to be mined for profit.
Explain why fossils are usually only found in sedimentary rocks.
Fossils are usually found in sedimentary rocks because they form from layers of mud and sand that gently bury and preserve dead remains.
What is streak?
It is the colour of a mineral in
powdered form
What is cleavage
Cleavage is when a mineral breaks in smooth, straight lines
What is fracture?
Fracture is when it breaks in rough or uneven shapes.
What are the 4 types of fossils?
Body fossils – preserved parts of the body like bones or shells.
Mould fossils – an imprint or shape left in rock.
Resin fossils – when an organism gets stuck in sticky tree sap and the body gets preserved
Trace fossils – signs of life like footprints, burrows, or leaf prints.
How do scientists use fossils for relative dating?
Fossils help scientists tell how old rocks are, because rocks with the same fossils usually formed at the same time.
What is a fossil?
A fossil is evidence of past life, that has been preserved in rock.
What parts of an organism are most likely to become fossilised?
Hard parts like bones, shells, teeth, and wood are more likely to be fossilised.
Distinguish between a cast and a mould fossil?
A mould fossil is the hollow imprint left behind when an organism’s shape is pressed into soft sediment.
A cast fossil forms when minerals fill that mould, creating a copy of the original shape.
