I'm not an expert on paving material. The driveway is black, has
settled a few inches over the old driveway (the one that ran down into
the garage) and has some cracks in it. I don't know whether there's
concrete under it, but I assume not.

It's been this way since I've owned the house (more than a decade) and
I don't think it was this sunken when I moved in, but since it's been a
long time I doubt it sinks that fast.