Let the holes dry out. When dry, fill each hole to the top with water and track the time it takes for the water to completely drain. If your holes are drained in less then ten minutes, the soils will dry out quickly in hot weather. Over a 24 hour time period track sediments. After the first few minutes measure depth of your sand layer.
Sand is very light in color, drains fast and is easy to work in.
Its draw back is that is not a fertile medium. In four or five hours the silt will settle, the color and texture is distinct. The color is a medium to dark brown and it has some fiber in it. Silt holds moisture reasonably well, it is fertile. However it can compact easily, so be careful not to walk or run heavy equipment over it.