What type of rock would likely be found in an ancient riverbed on the earth’s surface

I think it's sedimentary rocks, but I'm not sure.

In paragraph 47, it says “moments like these make a pioneering flight anything but dull” i’d say he’s optimistic and determined? ? and in 48, it describes how i’m assuming people he looks up to walked the same path so maybe he’s honored to be on the journey ? sorry if i’m wrong.

Idon’t understand are those songs? ?