For your consideration is this U.S. Geological Survey Monographs, circa 1891-1905. There are two surveys in this collection. The first is titled “U.S. Geological Survey Monographs” and is by J.W Powell, Director book XVII Lesquereux; it is about the flora of the Dakota group and is his posthumous work. The second book is titled “U.S. Geological Survey Monographs” and is by Charles D. Walcott, Director book XLVIII Part I. – Text; it is about the status of the Mesozoic floras of the United States. The condition of these surveys is good, with wear consistent with their age and some browning to the pages due to age, as well. The measurements of these geological surveys are 11 3/4" x 9 1/2" for both the surveys.