IQII.] 



STEVEXSOX— FORMATION OF COAL BEDS. 



619 



the conditions between Enkhuizen. north from Amsterdam, and 

 Dordrecht, south from Rotterdam, as well as in localities east and 

 west from that line. It is unnecessary to give more than a few of 

 these as in any group the same conditions are found. Eighteen 

 borings are reported along the east and west line from Rotterdam 

 to the Hook of Holland. Seven of these follow, the measurements 

 beinsf in meters and the numbers are those of the records : 



Sand and clay 4.5 



Peat 0.9 



Sand and clay 



Peat 



Sand and clay 



Peat 



Sand and clay 



Peat 



Sand and clay 



Peat 



S-. 

 3-9 

 14 



ss. 



3-2 



30 



So. 



6.0 



1-5 



5-1 

 2.6 



0.5 

 0.3 

 6.0 

 i.o 



103. 



4-5 

 Z-2 

 2.5 

 0.5 

 0.1 



0.5 

 1-5 

 1.0 

 1.2 

 1.0 



These exhibit the variations to a depth of 16 meters. The mate- 

 rial in each case below the lowest peat bed in the column is sedi- 

 mentary clay and sand. Peat was found in some localities at 19 

 meters, but it is never continuous to that depth, being always divided 

 by sediments. The greatest continuous thickness found in any 

 boring is 10 meters. At times the peat is replaced wholly by sedi- 

 ment and one can trace old river courses in which no peat was 

 formed and which now are filled with the transported sediment. 

 The records show the conditions in an area of 70 by 20 miles, 

 throughout which one finds one or more beds of peat covered with 

 a greater or less thickness of sediment. These are autochthonous, 

 and they contain stems of trees rooted in the subsoil. The inter- 

 vening deposits are often distinctly marine in many parts of ?Iol- 

 land ; a section by Lorie shows 



Meters. 



1 . Peat 3.2 



2. Gray clay, sandy below, calcareous, marine diatoms below, 



plant remains in upper part 0.8 



3. Argillaceous sand with Cardhim and Scrobicularia .>Q 



4. Black peat 05 



5. Tough grayish blue clay i.i 



6. Black, hardly coherent peat 1.2 



217 



