72 Professor G. Forchhammer on the Downs of Denmark, 



lowed the expression, contains a peat, which is not at all dif- 

 ferent from tlie peat of the rest of the moors of the district, 

 the portion of it which lies under the drift-sand is converted 

 into quite another substance. Our usual moor-peat weighs 

 16 — 20 pounds the cubic foot ; that which has been compressed 

 by the sand weighs 78 pounds. In our usual peat, after it has 

 been dried, there is hardly a trace of stratification perceptible ; 

 but in the other, the stratification is very distinct, nay, the 

 structure is almost slaty ; and when we compare it with the 

 sides of an excavation in fresh peat, we see plainly that the 

 thin layers contain the product of one period of vegetation, 

 therefore of one year. When, therefore, as is the case in North 

 Seeland, the peat-moor is chiefly formed by the destruction of 

 a forest vegetation, it is impossible to distinguish, in hand 

 specimens, this peat covered with drift-sand from brown coal. 

 Between the villages of Lyngbye and Lokken in Vensyssel, 

 there is a similar bed of Martorv about 15 feet above the level 

 of the sea. It reposes unconformably on blue clay, and in such 

 a manner that the strata of Martorv are gently inclined on 

 both sides towards the middle, where a small stream flows, 

 which interrupts the bed of peat, and has cut deeply into the 

 underlying clay. The bed of Martorv passes completely, in its 

 continuation sidewards, into black earth, and this latter, as 

 well as the peat, are covered by stratified masses of drift- 

 sand. If we pursue this little valley, we find, when we have 

 left the downs, a little stream, which in this place, as almost 

 everywhere in Denmark, is surrounded by meadow-peat, and 

 thus we have here a full explanation of the interesting phe- 

 nomenon of the formation of this bed of burning material which 

 has already become fossil. A three-fold system of strata pre- 

 sents itself in this cliff". The lower blue clay, a marine for- 

 mation of the present period, is inclined under an angle of 5° 

 to 8° to the south, then the fresh- water formation of the Mar- 

 torv^ with its northern and southern dip, and, lastly, the downs, 

 -snth their varied, often highly inclined, stratification. Fig. 3, 

 Plate 3, exhibits distinctly this appearance. 



At another point the Martorv^ which is also there covered 

 by down-sand, reposes on horizontal strata of blue clay full 

 of Cardium edule and Mytilus cdidU. As the peat GontaingI 



