The duties of the board shall be to determine the site of and to designate Mississippi landmarks; to remove from such designation certain of such sites as hereinafter provided; to contract or otherwise provide for the discovery and salvage operations herein covered; to consider the requests for and issue the permits hereinafter provided for; and to protect and preserve the archaeological, historical and architectural resources of the State of Mississippi. The board shall be the legal custodian of all items hereinafter described which have been recovered and retained by the State of Mississippi, and shall maintain an inventory of such items showing the description and depository thereof.