There will be what is called a "metes and bounds" description of the property.  If you start your search out at the appraisal district where you can search the address of the property, as with other properties it usually gives a brief legal description on it- 7.50 Acres out of the JW Smith Survey.  In the deeds the legal can be followed by doing just what it says go North this amount, South this amount, etc. and follow the roads and highways it references along the way.  These are sometimes subdivided from the first deed so you have to be careful not to miss it changed from 1,000 this way to 100.  There are Abstract Maps just like platted subdivisions that you should be able to view - JW Smith Survey, Abstract 128.  Unlike subdivision plats that are housed in the county clerks office, most abstract maps can be viewed at the appraisal district office.  Here we even have city block maps for larger cities like Dallas county.  If you get a chance to hang out at the appraisal district some afternoon you would probably be able to ask some questions.  Those of us that do large highway projects are in there reading abstract maps and finding easement information on old county and city road easements.  Hope that helps a little - I know it is a lot more complicated than this but it will start you in the right direction.  I don't know what experience you have but unless you have a long background in real estate or real estate law, I would not attempt these types of searches as they can become very difficult and liability can be very high - abstract maps are often way behind the present day ownership and acreage in a lot of the big counties - it just gives you a starting point and/or helps find some of the older easements that are quite hard to find in an entire room of books seven levels up per aisle in Dallas county  - and we even leave smiling sometimes - cuz it is just a nice day out!