A river runs through it!

Based on the image, the rock appears to have a layered structure with a mix of colors, predominantly gray with some yellowish-brown areas. This suggests it could be a type of banded iron formation or possibly a metamorphic rock like slate or schist. Banded iron formations are known for their alternating layers of iron oxides and silica or chert, while slate and schist are metamorphic rocks that can show similar banding due to the alignment of minerals under pressure and heat.