So, here's what I'm trying to do: I want to detect avalanche debris of a known avalanche using Sentinel-2 optical imagery. I've calculated the Normalized Difference Snow Index and from there I've extracted all the values above 0.4 which gives me a raster file that contains all the snow for the scene. There, I can easily recognise the avalanche debris that lie below the snow line based on their distinctive elongated tongue shape.
Is it possible for ArcGIS (or any other application for that matter) to identify and extract these elongated tongue shapes? Basically what I want to end up with is a file that contains nothing but the avalanche debris without manually selecting them.
I'm rather new to ArcGis so I have no idea if this is super trivial or practically impossible.
Edit: I've attached a picture of the avalanche in question. Note that the blue raster is the approximated snow line (this was done with simple generalization tools, though I have yet to optimise this). The red raster is all the snow below this snow line from which I'd like ArcGIS to detect elongated shapes like the one in the center of this picture.
Edit2: Thank you Xander Bakker for your answer, that is very close to what I was looking for. I have a second quesion though: How would I go about calculating the volume of the debris? I have a 10m DEM and I know the extent of the debris, so it should be possible to calculate it. The problem that I have is that, as opposed to calculating the volume of a lake for example, I don't have a universal z value that would allow me to easily calculate the volume above or bellow said value. The debris start at a highter altitutde as opposed to where they end. I have a attached a picture of the avalanche in ArcScene. I hope I explained that clearly, I don't really know the correct terminology.