Fróðskaparrit - 01.01.1975, Síða 109

Glacial Erratics
117
become shallower outwards and that at least the northern one
is probably filled with Quaternary sediments. Thus the troughs
therefore were probably sculptured by glaciers. However, the
relative abundance of local erratics on the continental slope does
not seem to be higher off the northern trough than off the
banks, and therefore this trough has probably not been eroded
much during the last glacial epoch and may date back to an
earlier glacial epoch or possible even to the Tertiary.
Acknowledgements
This work is part of a marine geological research program
carried out by the Faroe Government in collaboration with
the Geological Survey of Denmark.
The work has been supported by grants from »Statens Natur-
videnskabelige Forskningsraad« to the Geological Survey of
Denmark (O. Berthelsen, director) and to R. Waagstein. The
Fishery laboratory in Tórshavn has provided ship time and we
also received support from the Mineralogical Museum of the
University of Copenhagen.
We thank F. Bertelsen for providing palynological datings
of the sediments, and A. Noe-Nygaard, J. Bailey and N. Hald
for suggesting many improvements to the manuscript. We also
wish to thank the captain and crew of the »J. C. Svabo«, Kr.
Meitil and all others who have assisted us during this work.
ABSTRACT
On the outer shelf and slope south-east of the Faeroe Islands down
to 300 meters depth, 82 percent of the erratics consist of basalt and 14
percent of tuff carbonate sediments. At 400 to 700 meters depth these
rock types only constitute 54 percent of the erratics, the rest being mainly
sandstones and gneisses of distant origin. This sudden increase in the pro-
portion of foreign erratics is probably caused by the front of the Faeroese
ice sheet preventing ice-rafting over the shelf during the last glacial epoch.