Author
Pennsylvania. Bureau of Topographic and Geologic Survey
11
Willard, Bradford, 1894-
7
New Jersey Geological Survey
6
Pennsylvania Geological Survey
6
Geological Survey of Pennsylvania
5
Jackson, Charles T. 1805-1880
5
Fettke, Charles R. 1888-1959
4
Frazer, Persifor, 1844-1909
4
Geological Survey (U.S.)
4
Geological Survey of New Jersey
4
Lyell, Charles, Sir, 1797-1875
4
Pennsylvania. Department of Conservation and Natural Resources
4
Rogers, Henry D. 1808-1866
4
Rogers, Henry Darwin, 1808-1866
4
Wagner, Walter Richard, 1928-1974
4
Wyoming Historical and Geological Society
4
Clemson, Thomas Green, 1807-1888
3
Cook, George Hammell, 1818-1889
3
Eaton, Amos, 1776-1842
3
Lesley, J. P. 1819-1903
3
Lyman, Benjamin Smith, 1835-1920
3
Miller, Hugh, 1802-1856
3
Ridgway Farm and Land Company
3
Behre, Chas. H.
2
Butts, Charles, 1863-1946
2
Cate, Addison S.
2
Cleaves, Arthur B. 1905-
2
Dodge, Clifford H.
2
Dzombak, William C.
2
Ebright, John R.
2
Ely, John
2
Fackenthal, B. F. 1851-1941
2
Faill, Rodger T.
2
Foster, Margaret Dorothy, 1895-
2
Genth, F. A. 1820-1893
2
Geological Society of Pennsylvania
2
Geyer, Alan R.
2
Guer, Jean-Antoine, 1713-1764,
2
Heilprin, Angelo, 1853-1907
2
Hitchcock, Edward, 1793-1864
2
Ihlseng, M. C. 1852-1
2
Kiss, Edmund, 1886-
2
Lesley, John Peter, 1819-1903
2
Lesquereux, Leo, 1806-1889
2
Leverett, Frank, 1859-1943
2
Maillet, Benoît de, 1656-1738
2
Moyer, Forrest Theodore, 1906-
2
Norwood, J. G. 1807-1895
2
Owen, David Dale, 1807-1860
2
Pechin, William, 1773-1849,
2
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