232 COSMOS. 



it were the funnels of mines, indications of mine-like erup- 

 tions," resembling the remarkable phenomenon described by 

 me of the human bones scattered upon the hill of la Culca * 

 during the earthquake of Riobamba (4 February, 1797). 

 When single Maars, not situated at any great height, in the 

 Eifel, in Auvergne, or in Java, are filled with water, such 

 former craters of explosion may in this state be denominated 

 crater es-lacs ; but it seems to me that this term should not 

 be taken as a synonymous name for Maar, as small lakes 

 have been found by Abich and myself on the summits of the 

 highest volcanoes, on true cones of elevation in extinguished 

 craters : for example, on the Mexican volcano of Toluca at 

 an elevation of 12,246 feet, and on the Caucasian Elburuz at 

 19,717 feet. In the volcanoes of the Eifel we must carefully 

 distinguish from each other two kinds of volcanic activity of 

 very unequal age, the true volcanoes emitting streams of 

 lava ; and the weaker eruptive phenomena of the Maars. 

 To the former belong the basaltic stream of lava, rich in 

 olivine, and cleft into upright columns, in the valley of 

 Uesbach near Bertrich ; w the volcano of Gerolstein, which 

 is seated in a limestone containing dolomite, deposited in the 

 form of a basin in the Devonian grauwacke schists ; and the 

 long ridge of the Mosenberg (1753 feet above the sea) not 

 far from Bettenfeld to the west of Manderscheid. The last 

 named volcano has three craters, of which the first and 

 second, those furthest to the north, are perfectly round, and 

 covered with peat mosses ; whilst from the third and most 



90 Cosmos, vol. v, p. 173. I have twice visited the volcanoes 

 of the Eifel, when geognosy was in very different states of de- 

 velopment, in the autumn of 1794, and in August, 1845; the first 

 time in the vicinity of the lake of Laach and the monastery there, 

 which was then still inhabited by monks; the second time, in the 

 neighbourhood of Bertrich, the Mosenberg, and the adjacent Maars, 

 but never for more than a few days. As in the latter excursion I had 

 the good fortune to be able to accompany my intimate friend, the 

 mining surveyor, Von Dechen, I have been enabled by many years' cor- 

 respondence, and the communication of important manuscript memoirs 

 to make free use of the observations of this acute geognosist. I have 

 often indicated by quotation marks, as is my wont, what I have bor- 

 rowed, word for word, from his communications. 



91 H. von Dechen, Geognost. Uebersicht der Umgegend von Bad &> 

 trick, 1847, s. 1151. 



