C2-3
The Rock Cycle – Possible Pathways
The complete rock cycle showing all of the multiple pathways available.
The rock cycle does not always follow a sequential circular path (e.g., magma → igneous → sedimentary → metamorphic → magma). The complete rock cycle takes into account various physical processes that affect the formation of different types of rock.
- Weathering and Erosion: Weathering and erosion, in addition to acting on igneous rock, can also break down metamorphic rocks into sediments. These sediments can then form new sedimentary rock. Sedimentary rock itself can break down into sediments that can be used to form new and different sedimentary rock.
- Heat and Pressure: The same heat and pressure that transforms sedimentary rock into metamorphic rock can also convert igneous rock into metamorphic rock.
- Melting: All three rock types can be melted back into magma at any time, starting the cycle all over again.
History Link
The rock cycle is a continuous, interactive process. It has no beginning and no end. Rocks are continuously forming, changing, and reforming through the rock cycle.
Did You Know?
Melting Rock
A temperature between 625° C and 1,200° C (between 1,157° F and 2,192° F) is needed in order for rock to melt into magma. The exact temperature depends on the rock pressure and the chemical composition of the rock.
What Do You Think?
Source of the Sediment
Sediment can be transported into the ocean by a number of methods.
- Click here to zoom in on a heavy sediment area in the Bay of Bengal.
- Click here to add in country borders.
- Off which country’s ocean border is the deepest sediment located? The deepest sediment is located off the coast of Bangladesh.
- What is the sediment thickness off this country’s border? The sediment is 20 km thick off the coast of Bangladesh.
- Zoom in on the coastal area with the deepest sediment deposits.
- How is all this sediment being transported to the Bay of Bengal? What do you think? The sediment is being transported into the Bay of Bengal by a river (actually the confluence of the Ganges River and the Brahmaputra River).
- Click here to zoom in on a specific part of the ocean coast.
- Click here to turn off the sediment depth data for a “natural” view of the coast.
- What does this view now show? The current view clearly shows sediment being deposited around the river’s delta.
- Does this current view in the main view panel support your answer to how the sediment is being transported into the Bay of Bengal (i.e. question 3)? Answers will vary depending on the original answer to question 3.
- What is the original source of all of this sediment? What do you think? The sediment is caused by run-off from the surrounding land, and ultimately from the Himalayan Mountains.