Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in three basic forms: woven (resembling mail bag sacking) needle punched (resembling felt), or heat bonded (resembling ironed felt).  The District sells the woven style pictured below.