OF NORTH AMERICA. 
113 
Say, Morton, Conrad, Lea, and others, have described the Cretaceous fossils of North Ame- 
rica, and shown the justice of Vanuxem’s views, but they only extended his discoveries without 
materially changing them. It was Vanuxem, an excellent practical geologist, who pointed out the 
difficulties, and the others followed the path that he was the first to indicate and explore. The ad- 
ditions made to Vanuxem's divisions have not always been very successful ; thus Morton and Con- 
rad divided the Cretaceous rocks into three parts, the Upper, Middle, and Lower-, but Lyell has proved 
that the Upper division of Morton, embracing the White Limestone of South Carolina and Georgia, 
and the Numulitic Limestone of Alabama, belongs to the Eocene period of the Tertiary formation. 
Since Vanuxem, Sir Charles Lyell is the practical geologist who has contributed the most towards 
the perfection of the classification of the Cretaceous, Tertiary, and Quaternary strata, and the 
true limits of these rocks in the States bordering on the Atlantic, will be found in his memoirs en- 
titled : On the Tertiary formations and their connexion with the Chalk in Virginia and other parts of the United 
Stales (See: Proceedings of the Geological Society of London, vol. Ill, page 735. London, 1842.). 
On the Cretaceous strata of New Jersey and other parts of the United States bordering the Atlantic. — On the 
Miocene Tertiary strata of Maryland , Virginia , North and South Carolina. — On the White Limestone and 
other Eocene or older Tertiary formations of Virginia, South Carolina, and Georgia. (See: The Quarterly 
Journal of the Geological Society of London, vol. I, 1845.) 
Since the discoveries of Vanuxem and Lyell, the geologists who have done the most to make known 
the geographical extension of the Cretaceous and Tertiary rocks , are: Thomas Nuttall — Alabama , 
Arkansas, and the Great Bend of the Missouri, 1832 — ; Dr. Pitcher, U. S. A. — Alabama, 
Louisiana, Texas, and Arkansas, 1832-33 — ; Nicolet — Upper Missouri, 1842 — ; Ferdinand Roe- 
mer — Texas, 1848-49 — ; Evans — Mauvaises Terres of Nebraska, 1849 — ; Tyson and Dr. Trask 
— California, 1853-54—; Dr. F. V. Hayden — the Dacota country, 1855. 
Maclure regarded the Old Red Sandstone and the Carboniferous formation as belonging to the 
Secondary rocks , but in this he was mistaken , and xve have seen also that his Old Red was re- 
cognized by Hitchcock as New Red. It is true that at that time, 1809, the Paleozoic strata were 
entirely unknown, and there were only a few notions relating to the Mountain Limestone of Der- 
byshire , England (See: A Delineation of the Strata of Derbyshire , by White Watson; Sheffield 1811; 
and also ; Figures and Descriptions of Petrifications collected in Derbyshire, by William Martin ; Wigan, 1793.). 
Thomas Nuttall, the learned botanist, recognized the Mountain Limestone throughout the great 
calcareous platform of the Mississippi valley, as early as 1820 (See: Observations on the Geological 
Structure of the Valley of the Mississippi, Philadelphia, 1821.); and Eaton, in publications ranging from 
1818 to 1832, tried to classify the sedimentary rocks of New York State; although he was gene- 
rally not very successful in his determination of the relative ages of the strata, his works have 
contributed much to the development of American geology. It is, however, still to Vanuxem that 
we are indebted for the knowledge that the Secondary rocks of Maclure are Transition or Paleozoic 
rocks, and he more than any other geologist has helped to analyze and class them in their natural 
order. Vanuxem says in his First Annual Rep.rt of the Geological Survey of the fourth district of the 
State of New York, pages 189 and 190; Albany, 1837: dn 1827 and 1828, 1 travelled over a part 
«of Western New York, and a considerable portion of the States of Ohio, Kentucky, Tennessee, 
« and Virginia. The extensive collection of fossils, rocks, and minerals I then made, fully satis- 
