First off, for what you are wanting to do the correct test is to dig a trench so you can see the horizons in your soil.
You can do a finger test (rub a material between finger tips) to determine particle size, slickness and texture of that floating layer.
I don't know where on planet earth you live since you didn't fill out that part of your profile (please do that so others can offer pertinent advice in the future).
setting the area of interest to the county and then zooming in is the easiest way.
When you do the shake test, the clay will take a long time to settle on top of the silt. If it settles out quickly, it's silt. I imagine that what you have is silt. And maybe caliche which makes it extra hard.