258 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



of weakness. His description of basaltic inflows into sub- 

 terranean cavities formed by crust-expansion and elevation 

 anticipated later conceptions of laccolitic occurrences of 

 volcanic material. 



Before Von Buch had completed his work on the Canary 

 Islands for publication, the Englishman, Dr. Daubeny (1819), 

 published a tabulated summary of active volcanoes, together 

 with an enumeration of all volcanic and earthquake phenomena 

 reported within historic times. In 1824 the second volume 

 of Carl von Hoff's work appeared, and it embraced an ex- 

 haustive account of surface changes associated with volcanic 

 outbreaks and earthquake shocks. Von Hoff followed the 

 opinions of his compatriots, Humboldt and Buch, on all ques- 

 tions regarding the origin and destruction of volcanoes. 



A series of careful researches was carried out in the volcanic 

 areas of the Rhine Province by Johann Steininger, a teacher in 

 the Treves public school. Steininger established the differ- 

 ence between the volcanic rocks of the Eifel district and the 

 trap-porphyry rocks (melaphyre, porphyrite, palatinite) of the 

 district of Oldenburg and the Palatinate. Both were regarded by 

 Steininger as submarine in origin, but he referred the eruptions 

 to quite different geological ages. He pointed out that a 

 characteristic feature of the Eifel volcanoes was the frequent 

 occurrence of lava and volcanic slag and ash without any sign 

 of an orifice or eruption. The volcanoes of the Lower Rhine 

 district, especially the Siebengebirge, near Bonn, were explained 

 as upraised conical mountains in which the volcanic material 

 seldom escaped at the surface. In his Contributions to the 

 History of the Rhineland Volcanoes, published in 1821, 

 Steininger proved that a certain number of the volcanoes, 

 chiefly those on the right bank of the Rhine, had originated 

 contemporaneously with the formation of the brown-coal 

 deposits (Tertiary), and were therefore older than the pebble 

 and clay deposits with fossil mammalian bones (mammoth, 

 rhinoceros); but, he added, the products of the youngest 

 volcanoes on the left bank of the Rhine seemed to be dis- 

 tributed above these pebble-beds, and might accordingly 

 belong to historic times. The idea of the quite recent occur- 

 rence of those volcanoes originated from a mistaken reading 

 of a reference made to the volcanoes of this area by Tacitus. 



In his earlier writings Steininger was under the influ- 

 ence of Von Buch's theory of elevation-craters, but his close 



