FORCIIIIAMMER ON THE BOULDER FORMATION. 269 



almost the whole of Fiihnen, most of the Danish islands of the 

 Eastern Sea, except Bornholm and the east coast of the peninsula 

 of Randers as far as Lubeck. In the duchy of Schleswig, the 

 beds of it so alternate with those of the Brown coal formation, that 

 no distinct limit can be traced, and I should thence conclude that 

 its oldest part is of the sub-Apennine date ; although, on the other 

 hand, a blue clay, sometimes with and sometimes without boulders, 

 is found also in the duchy of Schleswig and in other places, which 

 contains, in great abundance, fossils of a much newer period ; 

 among which are Cyprina islandica, Corbula nucleus, and the 

 vertebras of fishes. This blue clay is much used for brick-making, 

 and, in some of the pits in which it is dug for this purpose, it is 

 found to alternate with a boulder clay, the beds being inclined at 

 a high angle, but dipping in various directions and at various 

 degrees of inclination. Deep wells sunk in some of these pits 

 near Apenrade, in the duchy of Schleswig, have sometimes given 

 off suddenly large quantities of carbonic acid gas ; and, on one 

 occasion, in 1841, three men lost their lives from this cause in a 

 well they were digging, and which they had left the night before 

 free from gas. The gas remained from April to August in this 

 well, and rose and fell according to the state of the barometer, rising 

 as the mercury in the barometer sank. 



The distribution of the boulders in the boulder clay formation 

 is very important. Blocks, several cubic feet in content, abound 

 throughout : but none are so large as the remarkable boulder on 

 the east coast of Fiihnen which, in 1840, was standing 11 feet 

 above the ground, and measured 105 feet in circumference, but 

 which has since been shown to be embedded in the earth to a 

 considerable depth, 10 feet more having been now exposed, and the 

 circumference continuing to increase. 



All the larger blocks are of granite, granitic gneiss, porphyry, 

 syenite, greenstone, and quartz rock. Among the boulders of 

 smaller size firestone and fragments of the chalk formation begin 

 to appear and constantly form a larger proportion of the whole as 

 the size of the boulders diminishes. In order to compare the con- 

 tents of the boulders of different formations at different places, 

 I assumed, as mean sizes, those between the dimensions of the 

 closed single hand and the two hands together ; and I have now 

 made calculations with regard to several hundred from different 

 parts of the country which have conducted me to unexpected 

 results. 



In the line of junction between the limestone of Saltholm and 

 that very similar limestone which appears in the neighbourhood of 

 Greenaae in Jutland the boulders of the Saltholm limestone are 

 so common that upwards of 20,000 tons of them are annually 

 burnt for lime. The moment, however, that the line of junction 

 is passed, the boulders of this rock become rare, and soon dis- 

 appear ; so that since we cannot but assume that this bed continues 

 in the same direction beneath the other, it results that these boul- 

 ders have been very little removed from their parent rock. On 



