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of 4 K.M. from Odoorn, where the way from Eksloo to Brammers- 
hoop crosses the high road, boulder-clay is seen again, under 0.7 M. 
of boulder-sand; here it is partially of a yellowish brown spotted 
with greenish grey colour, a difference in connection with the not 
flowing off of the water in the soil. In sinking a well, this clay 
proved to have a thickness of 2'/, M. Farther north it is found 
at least as far as Ees. 
At 2, K.M. south-west of Odoorn, in the Peat-moss of Odoorn, 
that is in the midst of the Peat-moss of Schoonoord according to 
Lorik, the boulder-clay is wanting under the + 1 M. thick bed of 
boulder-sand, which came to light after the opening of the peat-moss 
for digging fuel. In its place a bed of light bluish grey clay, 0.3 
to 0.4 M. thick, is found. This was observed at a pit dug on purpose 
and is the case with the whole Peat-moss of Odoorn, as has been 
observed when digging ditches. This plastic clay, containing no 
palpable sand, is entirely different from the boulder-clay. It is 
hardly to be doubted that we have to regard it as lake-clay, the 
same as the wellknown preglacial Pot-clay from the underground 
of Drenthe, Groninghen and Friesland, which gave rise to peat-mosses 
in such cases where it was shaped in the form of basins. 
Thus the considered part of the Hondsrug, about the half of the Honds- 
rug in Drenthe and almost a third of the whole of that ridge which 
is extended from north-west to south-east, between Groninghen and 
Emmen, and is elevated only on an average 5 M. above the 
„surrounding region, is constituted by preglacial Rhine-sand, super- 
ficially covered, in the same manner as the adjoining ground, by a 
bed of boulder-sand not 1 M. thick. 
That the boulder-sand cannot owe its origin to washing out of 
the boulder-clay may be admitted for the following reasons: 
1st The hard boulder-clay offers great resistence to eroding agencies. 
This appears amongst others from its forming steep and more or 
less projecting parts at the coast of the Roode Klif, the Mirdummer 
Klif and the Voorst, and even isles, at Urk and Wieringhen. 
2°¢ Though undoubtedly the quantity of boulders in the boulder- 
sand has from the beginning been very variable, it is however a 
fact, that in the neighbourhood of the villages most boulders have 
already been dug out and that they were formerly very numerous 
almost everywhere. At some places one stone was lying next to the 
other in the sand. An average condition is to be met with at some 
parts of the Noorder Veld of Eksloo. Now to the north of pit XLV 
on a surface of 1500 M*. and to a depth of 0.5 M. there had been 
freshly dug out 40 M*. of stones, from the size of a child’s fist up to 
