Above: An Adjective or Preposition?

I was checking a grammar exercise created by a colleague and a question arose about the function of "above" in the following sentence:

If you have questions, you can look at my notes above.

She feels it's an adjective, and I feel it is a preposition. My reasoning is that if one removes "at my notes" "above" is giving further information in the way a preposition does.

So, which is it; a preposition or an adjective?

It can be used as either a prepositon or an adjective.

Above used as a preposition takes the following form: noun + verb + preposition + noun (e.g., ceilings are above floors, the plane flew above the clouds, I reached above me, etc.). This is its most common usage.

Above can appear, as an adjective, in the prepostitional phrase of an imperitave and tends to modify written text: command + prepositional phrase (e.g., meet at the above address, refer to the above text, call the above phone number, etc.). In each of these cases, however, it is implied that the noun being modified by the adjective, above, (i.e., address, text, phone number) is written above wherever the subject of the imperitave (i.e., the reader) reads the command. In other words, above is never non-prepositional.