Looks like the sandstone bedrock cracked in straight lines. The circular puddle reminds me of the picture below. I realize the round puddle you show has a flat side and does not necessarily represent the exact situation shown in mine. Keep hunting.
Well, I have trees on both sides of the creek and at each end of the creek with symbols carved into them. I considered that these could be cracks, but the thing that was confusing to me is that the line goes through several different rocks stacked on one top of another. There are also several large X and Y shapes in the creek bed. The thing is that it appears to be carved instead of cracked, there's no breakage. Hmm... so confusing.
dela check here again you will have to remove moss from rocks this is close to what im doing a small scale rangler called later part do u have any larger rocks half buried or wait till water goes down to see rocks in water
I think the puddle and the number 6 could be examined more closely. Around the puddle I would look for carvings. It might be natural from water falling and wearing a hole..on the other hand it seems to be an odd and very particular shape.
On creek pic 6, you may have a greyish artificially modified rock wedged in the crevice..looks like it has an ear or two. The circled figure caught my eye because of the triangular like hat it has on..though it is not a pure triangle, I think it is notched at the top. Possibly, this is a turtle head given the context you mentioned.
Not a lot of streams around here, so no comment on the lines in the bed. Except..what i do is when i am suspicious, is walk around and find some natural cleavage or forms..that might be similar..as a reality check.
So, to me, it all looks worth a closer look but not enough yet to say one way or another if it is modified or not.