In the following sentence:
Near the top of the 200-meter avalanche, disappearing under its 100-meter wide path, are the fresh tracks of two skiers.
I think the subject is "tracks", the verb is "are" and in this case intransitive.
I also think that "near the top of the 200-meter avalanche" is an adverb phrase modifiying "are".
And finally, I think that "disappearing under its 100-meter wide path" is a participial phrase acting as an adjective modifiying "tracks".
Am I right or am I way off?