Admin Table of Contents
- 1 What is an igneous intrusion and what is its age relative to the rock around it?
- 2 What is the age of an igneous intrusion compared to the rock layers it cuts through?
- 3 What is the process that turns an igneous rock into a sedimentary rock?
- 4 Is an intrusion younger or older?
- 5 What does the age of an igneous rock mean?
- 6 How absolute and relative dating determine the age of stratified rocks?
What is an igneous intrusion and what is its age relative to the rock around it?
A rock formation or surface that cuts across other rock layers is younger than the rock layers it disturbs. For example, if an igneous intrusion goes through a series of metamorphic rocks, the intrusion must be younger than the metamorphic rocks that it cuts through (Figure 11.12).
What is the age of an igneous intrusion compared to the rock layers it cuts through?
A crack in the rock layer is called a fault. When igneous rock (volcanic lava) intrudes or cuts through layers of sedimentary rock it is called an igneous intrusion. The principle of cross-cutting relationships states that a fault or igneous intrusion is always younger than the rock it cuts across.
What is the relative age of an igneous rock intrusion between domed layers of sedimentary rock?
Earth History
| Question | Answer |
|---|---|
| What is the relative age of an igneous rock intrusion between domed layers of sedimentary rock? | It is younger than the sedimentary rock. |
| How are sedimentary rocks formed? | By hardening and cementing of layers of sediment |
What is the process that turns an igneous rock into a sedimentary rock?
On the surface, weathering and erosion break down the igneous rock into pebbles, sand, and mud, creating sediment, which accumulates in basins on the Earth’s surface. As successive layers of sediment settle on top of one another, the sediment near the bottom is compressed, hardens, and forms sedimentary rock.
Is an intrusion younger or older?
An intrusion is always younger than the rock layers around and beneath it. A fault is always younger than the rock it cuts through. The surface where new rock layers meet a much older rock surface beneath them is called an unconformity. An unconformity is a gap in the geologic record.
Is igneous intrusions older or younger than layers A and B?
Igneous rock forms when magma or lava hardens. Lava that hardens on the surface is called an extrusion. The rock layers below an extrusion are always older than the extrusion. An intrusion is always younger than the rock layers around and beneath it.
What does the age of an igneous rock mean?
(The familiar word “lava” is used for magma that erupts onto the surface of the earth, and later cools and freezes to form a volcanic rock. That – the time passed – is the age of the igneous rock. The magma itself may have come into existence much earlier in Earth’s history, but not the rock.
How absolute and relative dating determine the age of stratified rocks?
Numerical or absolute age of the events is given using absolute dating or radiometric methods. Absolute dating provides the age for the ash layers while relative dating provides at least six strata with relative ages – first and last occurrences of the fossils and the volcanic eruption events.