In approximately 1500, which geographical feature was found in areas settled by both northeastern and southeastern american indians?

I'm interested in this question myself, I don't think Indians ever left physical structures behind, so I looked up a ton on geographical features left behind by Indians and not just in Northeastern and Southeastern America, because there are many types of Indians, but nothing came up on any type of Indian especially in the 1500's. I tried, but I don't think this question can be answered, I looked up this question in many different ways and broke it down to try and gather small pieces of information, but in the end there was no features known to be left behind by American Indians. If anything they left behind culture and methods of doing things. Hope anything I said helps even though I could not figure out the answer.
 

Ya why not. you can share answer meaning g to say u can ask and learn.