The following described area is added to and made a part of the Grand Canyon National Park: Beginning at the corner common to sections 14, 15, 22, and 23, township 30 north, range 4 east, Gila and Salt River meridian; thence west along the section line between sections 15 and 22 a distance of nine hundred and fifty feet; thence south a distance of one thousand three hundred and twenty feet to a point on the south line of the north tier of forties of said section 22; thence east a distance of one thousand six hundred and ten feet; thence north a distance of one thousand three hundred and twenty feet to a point on the line between sections 14 and 23; thence west along said section line a distance of six hundred and sixty feet to the place of beginning, containing an area of forty-eight and seventy-nine hundredths acres, more or less: Provided, That livestock permitted to graze in adjoining national forest areas shall be allowed to drift across the land described herein to private land north thereof within the park.