For the purpose of preserving in their natural state the outstanding scenic features thereon and for the purpose of rounding out the boundary of the Bryce Canyon National Park, the President of the United States is authorized, upon the joint recommendation of the Secretaries of Interior and of Agriculture, to add to said park by Executive proclamation any or all of the following-described lands in the State of Utah, which shall thereupon become and be a part of said park subject to all laws and regulations applicable thereto, to wit: South half southwest quarter section 2, south half south half section 3, southeast quarter southeast quarter section 4, east half section 8, sections 9, 10, west half section 11, west half section 14, sections 15, 16, east half, northeast quarter northwest quarter, east half northwest quarter northwest quarter, north half southeast quarter northwest quarter, south half northeast quarter southwest quarter, north half south half southeast quarter northwest quarter and north half southeast quarter southwest quarter section 17, south half south half section 19, south half northwest quarter section 20, west half, west half east half and northeast quarter northeast quarter section 22, north half northwest quarter section 23, west half section 27, and north half northwest quarter section 34, township 36 south, range 3 west; lots 3 and 4, south half northwest quarter section 4, northeast quarter northeast quarter and southeast quarter southeast quarter section 8, township 37 south, range 3 west; west half east half and southwest quarter section 25, unsurveyed township 36 south, range 4 west; lots 3 and 4, south half west half section 3, lots 1, 2, 3, and 4 and south half section 4, and lots 1 and 2 and south half east half section 5, township 39 south, range 4 west, Salt Lake meridian: Provided, That nothing herein shall affect any valid existing claims upon the lands herein authorized to be added to the park or the rights of stockmen to continue to drive stock over the lands now under an existing stock driveway withdrawal.