How does magma change into a sedimentary rock?

Answer 1

The magma hardens into igneous rock, and then breaks up into small pieces due to weathering (over millions of years); the weathering process deposits it in strata through the action of water or wind.

Then under pressure (normally of the continued depositing of more layers of rock and sand above it), the particles compress together to form a sedimentary rock layer. Again this process can take tens of millions of years.

An example of this is Granite, which is an igneous (magma-type) rock, on weathering and reconstitution it can become sandstone.

Answer 2

Magma can change into a sedimentary rock through a process called weathering and erosion, where the magma is exposed to the Earth's surface, breaks down into smaller pieces, and is transported and deposited as sediment. Over time, these sediments accumulate and undergo compaction and cementation to form sedimentary rock.