The following words and terms, when used in this chapter, shall have the following meanings, unless the context clearly indicates otherwise.     
       (1) Avoidance Margin--the area around a significant magnetic anomaly or sonar target in which the proposed activity cannot occur, i.e. the anomaly or target must be avoided by the margin, unless the source of the anomaly or target is investigated and shown, to the satisfaction of the commission, to be not historically significant or is mitigated in some fashion approved by the commission. The avoidance area will generally be defined by a circle or oval, the outer limits of which are separated from the approximate outer edges of the contoured magnetic anomaly by the appropriate avoidance margin.      
       (2) Commission--the Texas Historical Commission.      
       (3) Person--any individual, firm, partnership, association, corporation that is public or private and profit or nonprofit, trust, political subdivision, agency of the state, or agency of the federal government who conducts or causes to be conducted any activity which would cause damage to a state archeological landmark.      
       (4) Shipwreck--any watercraft or aircraft that is 50 years old or older, including any part of them or contents of them, and is sunken or abandoned in, on, or under the surface of any land, including submerged land, belonging to the State of Texas or to any county, city, or other political subdivision of the state.      
       (5) Significant magnetic anomaly--best engineering judgment should be used to determine if the source of a magnetic anomaly might be historically significant. Determination of magnetic anomaly source significance must be made by a person experienced in the archeological interpretation of magnetometer data, taking into consideration the amplitude, duration, orientation, and complexity of each anomaly or anomaly cluster.      
       (6) Significant sonar target--best engineering judgment should be used to determine if the source of a sonar target might be historically significant. Determination of potential target source significance must be made by a person experienced in the archeological interpretation of sonar data, taking into consideration the size and shape of the visible target and any associated magnetometer data which might reveal the potential for buried, unseen parts of the target.      
       (7) State Archeological Landmark--any cultural resource located in, on, or under the surface of any land, including submerged land, belonging to the State of Texas or to any county, city, or other political subdivision of the state, or a site officially designated as a landmark at an open public hearing before the commission. Any pre-twentieth century shipwreck is automatically a state archeological landmark. Any shipwreck, as defined in paragraph (4) of this section, that is not pre-twentieth century but meets the criteria under §26.9 of this title is also eligible to be officially designated as a state archeological landmark.      
       (8) Submerged land--land belonging to the State of Texas, including its tidelands, submerged land, and the beds of its rivers and the sea within jurisdiction of the State of Texas or any political subdivision of the State of Texas.      
     Source Note:        The provisions of this §28.2 adopted to be effective March 18, 2003, 28 TexReg 2316; amended to be effective August 21, 2008, 33 TexReg 6582