Dear Madame L,
If a person owns a piece of land do they own it all the way down to the core of the earth and up into space?
Unfortunately, you probably own only the very surface of your land. Someone else can buy mineral rights to your land (and this includes gas and oil rights), or you can buy those rights yourself, if you think there may be something beneath the topsoil that's worth digging for.
If you have any concerns about this, check with the Realtor who sold you the property and/or get some legal advice.
Yours to the core,