Tegelen, though the localities are only a short distance apart. And when we compare 

 the floras of the two deposits, the difference is even more striking, as will be shown 

 when we discuss the botanical evidence. There seems no doubt that the nearly contin* 

 uous series of clay*pits above Reuver and Swalmen are in a single bed, which represents 

 a stage below the water4evel and inaccessible further north, unless it be represented by 

 the disturbed deposits of Wylerberg. 



The Reuver pits show a thick bed of grey loam, with leaves in the lower part; 

 above this come carbonaceous strata with more lignite and numerous seeds. It is from 

 this upper part, which is rejected by the brick*makers as too carbonaceous, that our 

 collections have been made. Thick roots penetrate the loam and pass down into the 

 underlying sand, proving that some at least of the trees grew .on the spot. A great deal 

 of the lignite and many of the seeds may however have drifted for a considerable 

 distance, for the upper part of the deposit seems to have been brought by floods. The 

 leafsbearing clays below yield also a few badly*preserved freshwater mollusca, including 

 Anodon, but no vertebrate remains have yet been found. This part of the deposit seems 

 to have been formed in an abandoned channel or backwater, with little or no current ; 

 for though the sediment is so fine, the beds are curiously irregular. 



Still further south, but forming an almost continuous series with those of Reuver, 

 are the Swalmen pits. In these the clay is comparatively thin ; but shows a similar sue* 

 cession, with grey leafsbearing loams below and more carbonaceous seed*bearing clays 

 above. Here also the loams and underlying sands are penetrated by vertical roots. 



The fourth locality from which collections have been made is Brunssum, near 

 Heerlen, a long distance south of the other pits. Here some small pits in the middle 

 of the heath show 1 to 1.5 metres of very carbonaceous clay, full of lignite, fruits, seeds, 

 and badly preserved leafsfragments. The whole deposit is penetrated by small vertical 

 roots, which have tended to injure the fossils. These carbonaceous clays rest immediately 

 on the pure white Miocene sand, and in some roadscuttings near the coal-mine have 

 been seen to be faulted against the Miocene strata. The Miocene is also of freshwater 

 origin, and contains masses of lignite, which were penetrated in sinking the neigh* 

 bouring coal*shaft. This Miocene lignite however is quite unlike the Pliocene. It is hard, 

 compact, and forms a true brown coal. The seeds found in it are all unknown in the 

 overlying Pliocene strata. Below these Miocene lignites are found marine Middle Oligo* 

 cene strata, so the exact date of the Miocene lignite is still unknown. 



Brunssum lies a long way south of the other plantsbearing localities, and its flora 

 differs somewhat from that of Swalmen and Reuver, though the deposits are probably 

 contemporaneous. This difference can perhaps be correlated with the lithological change 

 in the gravels. The gravels of Reuver and Swalmen are mixed gravels of the Rhine and 

 Maas, and the plants there found may have floated down either river. Brunssum, 

 however, lies above the old junction of the rivers, and its flora should therefore be that 

 of the Maas basin alone. This geographical difference seems sufficient to account for the 

 differences in the floras, for though it is possible that the clays may be of slightly 



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