Soil extension office would have soil maps and someone that can read them. This is critical to find depth of soil (before rock) for foundation plans like basement. Also, soils are critical to find if there is any grey clay in the area. Grey clay absorbs water, swells and shrinks and is killer on foundations. If there is any evidence of grey clay, the best insurance is to plan on doubling your footer. So if standards call for 18"x 24", make it 36" x 48" (I am not kidding).
Search for tax records: search internet based on your county name and GIS. There should be a link for Parcel Viewer (ISV). This is typically a free viewer to look at tax records. You can go to the map and find the location or enter a owners last name many times names are common so you have to sort it out with the map.