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Oberahn near Sande in the bay of Jahde lies 1.0 m. above A. P. In 
the Mound at Farmsum the foundation lay 0.65 m. below A.P., but 
it rested on 0.4 m. of clay and almost 4 m. of Idw peaty ground. 
So it is clear that the situation of the foundation does not betray a 
sinking, but a shrinking of the thick peat-layer. 
Two Frisian Mounds, which rested on diluvial sand, presented a 
succession of layers, which pointed to a post-diluvial lowering, so a 
lowering of earlier times, before the erection of the Mound. 
On the diluvial sand, (brown on the upper side), followed: 
1. A layer of high peaty ground, which contains “rietstokken” 
(reeds intercrossed with roots) in the lower parts, higher however 
it contains heather, peat moss, birch wood etc. 
2. On this a layer of clay with “kwelder” vegetation. This layer is 
1,5—2.0 m. thick under the Mound of Dokkurn. In the lowest parts 
it contains remains of Triglochin maritimum. 
So the original surface was diluvial sand. 
But since the ground sank and was flooded, sb that a vegetation 
arose in water, which gradually was decomposed and formed a layer 
of low peaty ground. The sinking of the ground continued, so that 
clay was washed ashore and deposited by the sea-water. On this sea- 
clay the Mound was afterwards built. Together the layers are ±3 m. 
thick near Dokkum, and to this cypher must amount the post-diluvial 
sinking, which extended over thousands of years, for the above- 
mentioned Mounds have taught us that no sinking has taken place 
for the last two thousand years, or only an insignificant one. After 
the deposition of the sea-day the post-diluvial sinking must have 
ceased, or at least have become very slight. 
J. Martin furnished some data on the Mounds in Oldenburg. 
In the Mound at Bant the floor lies 0,3 m. below the arable 
land, and cannot have been much higher; for the “kwelder” outside 
the dike does not lie higher. The ground was rediked in 1529. 
The Mound between Ellerdem and Sande, on which a church used 
to stand in former times, has a recognisable floor, i. e. a sand-layer, 
which includes a layer of bog, and lies 0.3 m. below the arable ground. 
The Mound at Haddien in Jeverland contains a layer of knik-clay 
which contains many shards down to 1,06 m., under which, sharply 
defined, a bog layer from 1,1 to 1,5 m. Here the floor lies about 
at the same level as A.P. The Mound contains many urns with 
burned remains, hence it dates from the pre-Frankish time. 
A Mound at Tettens has a floor which lies 1.2 m. below the 
level of the “kwelder” outside the dike (= 0,30 above A.P.). 
