306 REPORT OF NATIONAL MUSEUM, 1904. 



And this from a paleontologist! 



Although the geological map referred to on page 219 was the most 



important of Maclure's works and the one upon which his fame as a 



geologist largely rests, there are at least two papers of later date that 



are worthy of consideration. The first of these bears 



the west indies, the title Observations on the Geology of the West 



1832 



India Islands from Barbados to Santa Cruz, Inclu- 

 sive. This was printed for the author in pamphlet form in 1832, 

 while he was at New Harmony, Indiana. The mineralogical nature of 

 the materials composing the islands was noted as well as many of the 

 structural features. He thought to divide the islands into two distinct 

 classes on geological grounds, the first, or most eastern, comprising 

 the islands of Barbados, Marie Galante, Grande Terre in Guadeloupe, 

 Desirade, Antigua, St. Bartholomew, St. Martin, Anguilla, and Santa 

 Cruz. These he found composed mainly of shell-limestone or madre- 

 pore rock belonging to the transition class, though sometimes capped 

 by secondaiy rocks. The second class, including the Grenadines, St. 

 Vincent, St. Lucien, Martinique, Dominica, Basse Terre in Guade- 

 loupe, Montserrat, Nevis, St. Christopher, St. Eustatia, and Saba, 

 were more or less volcanic and regarded as probably thrown up from 

 the bed of the ocean. Such an origin he felt to be proven by their 

 containing intermingled masses of volcanic rock and coral or madre- 

 pore limestone. The idea that volcanic activit}' was dependent upon 

 combustion, as the word is commonly used, still prevailed with him, 

 and from the fact that the line of islands corresponded closely with 

 the strike of the rocks composing them he thought that the seat of 

 combustion probably existed in some stratified substance running par- 

 allel to the general stratification of the surrounding rocks. Further, 

 since he found on the islands soufrieres which deposited sulphur as 

 well as formed alum rock, he concluded that sulphur was one of the 

 combustible ingredients. 



Maclure's second paper referred to, An Essay on the Formation of 

 Rocks, or an Inquiry into the probable Origin of their Present Form 

 and Structure, appeared in 1838. In this the rocks were divided 



into three classes: First. The Neptunian, including 



Maclure on the . , . . * 3 "■ 



Formation of Rocks, those plainly ot aqueous origin. Second, the volcanic - 

 and third, those of doubtful origin, under which head 



he would place gneiss, mica, and clay slate, primitive limestone, sye 



nite, granite, greenstone, etc. 



In 1832 the melancholy Conrad began the publication of his work 

 on the fossil shells of the Tertiary formations of North 



Conrad's Tertiary of . . 



North America, " America. This marks, according to Dr. G. D. Harris, 



1 832 



"the beginning of systematic research into this part 

 of our continent's history." 



The work was published in parts and in small editions, largely at 

 Conrad's own expense, the numerous plates of illustrations being pre- 



