Dangling Modifier: a modifying word or phrase that is not properly matched with the word it modifies. Dangling modifiers often occur at the beginnings of sentences.
-Traveling north, the trees get smaller.
In this sentence, traveling north is meant to decribe the person who travels, but it's actually describing the trees, which don't travel at all. A correct version would be:
-Travleing north, I notice that the trees get smaller.
