"accidental" compost

Good morning!
I'm new to permies and permaculture in general, so I thought I would pose a question to my new expert friends! I recently moved into a house that is built on a steep, wooded hill. At the bottom of this hill is a fence for a dog run, which appears to have been installed around five years ago. As you can see in the picture, around 10 to 12 inches of soil has accumulated from leaves collecting against the uphill-side of the fence. After coming to the conclusion that this is simply an accidental leaf composting endeavor, I began to wonder if I could treat the soil like actual compost and use it as such in my raised beds. While I am certain that the soil is comprised of mostly decomposed leaf matter, it's unfortunately not of the same loose, rich consistency that you typically see from a hot compost pile. It seems possible that water erosion from the steep nature of the hill has washed out much of the larger organic material. Which brings me to my question - should I treat this as a nutrient-rich soil from a natural (minus the fence) composting source? Or, since much of the larger organic material is gone and was likely washed away, should I simply treat it like any other soil that someone could dig from their backyard? Is there any way to test the soil for its nutrient qualities?

Any input or suggestions would be wonderful. Cheers and thank you in advance!
-James

I'd dig some of that up and see what it looks like, if it looks like good, finished compost then I'd just use it that way.
On the other hand, if it hasn't fully decomposed to compost, just re-compost it for a while and your off to the races.

What I've found on Buzzard's Roost is that when the wind does the job of piling up the leaves for us, we end up with leaf mold not compost.
The leaf mold is just as valuable though so we use it in our vegetable gardens.

I've got similar areas on my patch of land and this is what I deduced : it rains, leaves clog the fence then start filtering the water, leaving sediment behind. So mine is a mixture of uphill sediment, leaves, sticks, etc

It's good stuff for sure.