Onshore drilling in Kefalonia – 2011 Interim Research SummaryDownload the full text of the Interim Research Summary.
During 2011, the project sponsors Fugro acting upon the advice of Professor Underhill have performed land-based shallow (less than 100m) drilling using a small mobile rig. That drilling program has enabled continuous rock-cores to be obtained at a number of locations in Kefalonia, mainly in the Thinia valley.
The core samples were transported to Fugro’s geospecialist labs in North Wales in late 2011 and are currently being logged, sampled and analysed.
Whilst it will take further time for the overall results to emerge, some of the preliminary indications are of particular interest, as follows:
- Borehole cores from the Thinia valley indicate that some very large in-situ rock segments of Cretaceous and Paleogene age period overlay (i.e. have been thrust on top of) rock segments of the younger Plio-Pleistocene period. This confirms that the pre-existing sidewalls of the Thinia valley have themselves been translated westward as a result of relatively recent co-seismic activity. This result represents a “tectonic” disruption of the Thinia valley.
- On the south-west flank of the Thinia valley in an area called Katachori, there is clear evidence that a major rockfall has originated from the eastern slopes of the valley, travelled across the valley floor and has come to rest (onlap) upon the upwards-sloping western hillside, infilling the valley itself in the process. This can be confirmed on site and via helicopter-based LIDAR scans, and it is also visible via Google Earth imagery.
- The tail end of the rockfall has covered some pre-existing walls which end abruptly at the debris and their continuity can be identified underneath it. Upthrust combined with rockfall and valley fill set up a barrier for drainage that caused an ancient lake to form subsequently above it. The lake bed has now silted up and forms a low-agricultural plain in the centre of the valley.
- Elsewhere in Thinia the drill-core samples indicate that rockfall debris covers former marine beach deposits (e.g. at Zola on the north-western end of the valley) and work is ongoing to determine the age of the buried sediments.
» Marine deposits have already been discovered at some locations along the Thinia isthmus, and at present the aerial tests, the land-based observations and the results of the core sampling to date support the tectonic infill proposal. If a tectonic infill can be demonstrated then this will also indicate that the former coastline was not a long and narrow marine channel, but may have been a significantly wider and more naturally shaped marine seaway that resembled the existing bays to the north and south.Download the full text of the Interim Research Summary.