We find them in the stream valleys.

我们在河谷里发现过它们。

And we can go out in the modern world to look at a stream valley versus a desert, versus open plains, and each of them has a different pattern of sediment being produced and therefore different types of sedimentary rocks or structures.

我们可以去现代世界观察河流峡谷对比沙漠，对比开阔平原，它们每一种都会产生不同类型的沉积物因此会有不同的沉积岩或沉积结构。