* Sedimentary rocks: These are the most common types found in rivers. They are formed from the accumulation of sediments (like sand, gravel, and mud) that have been eroded and transported by the river. Examples include sandstone, limestone, and shale.
* Igneous rocks: These rocks form from the cooling and solidification of molten rock (magma or lava). They can be found in rivers if the river flows through areas with volcanic activity or if the river erodes older igneous rocks. Examples include granite, basalt, and obsidian.
* Metamorphic rocks: These rocks form when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat, pressure, or chemical reactions. Metamorphic rocks can be found in rivers if the river erodes through areas of metamorphic rock formations. Examples include marble, slate, and gneiss.
So, the answer to your question is: all three types of rocks can be found in and around rivers.
