In early October Tim Raub and I were invited to join Dr Fanny Bessard and Dr Paul Churchill as part of a pilot study of the valley to ascertain if there were suitable records to investigate the role of climate, environmental change and natural hazards in the history of the country.
Our first tasks at the now ruined city of Dvin was to determine the environment and possible original reasons as to why the town was founded at this particular location. There is evidence of site occupation stretching back to at least early bronze age as the site stands proud of the surrounding landscape. Close inspection revealed a bedrock base that is likely a gravel terrace remnant of the old piedmont surface extending from the mountains to the east. This has been dissected in parts by a series of river channels which today have either dried up or been modified to harness the water for irrigation purposes. While Tim mapped the geology, I undertook frequency domain electromagnetic surveys in the hunt for the channels and their relationship to the outside walls of the old city. The results were combined with digital terrain and photographic models that show great promise for our future work.
Armed with the knowledge that water supply from the uplands likely played an important controlling factor in both rural and urban centres we moved our investigation up to the hills. Immediately to the east the geology consists of mainly sedimentary rocks and in particular Permo-Triassic limestone (more on this later). To the north east however, the geology quickly gives way to igneous complexes associated with the numerous volcanic centres in the region.
While the climate, and thus rainfall patterns
are similar, these different geologies manifest themselves in very different
hydrology and scenery. On the sedimentary rocks, fast flowing but ephemeral
streams erode steep valley sides whereas the igneous terrain tends to a rolling
landscape with more sustained overland flow of streams and rivers. This means no way of capturing the water in
the south in reservoirs, rather the natural springs have to be tapped at
source. However, in the north the hunt
is on for where water storage schemes might have been built. Means for the transport of water is in
evidence everywhere. Leets run parallel
to many hillsides and mark the stark contrast from barren land above the leets to
lush agricultural land below. Evidence
of buried water conduits in the form of clay pipes of all manner of size and
shape have been unearthed from highland villages to the towns across the valley
floors. Tracing these will be a priority for future work and trying to understand
the pattern of distribution and timing of their construction and demise could
be crucial to an understanding of the history. For example, what happened to
them when earthquakes struck?
|Temple of Garni|
The second site was in the sedimentary sequences to the south and when approached from the southern road out of Lake Sevan you are confronted by a sudden drop-off into the steep limestone valleys that reveal a 1200m section of limestone and calcareous shales with hues from pink to cream that represent one of the best exposures of the Permian to Triassic mass extinction event anywhere. The extent of the exposure is quite remarkable both laterally and in the vertical transition. Great student mapping projects to be had here!
The third site he wanted to visit was to the east at Lake Sevan. This large upland lake sits along the Spitak fault that marks the juxtaposition of ophiolite complexes to the east with the basalt and sedimentary sequences that lead down to the Ararat Valley. The fault, as with many other ones in Armenia, is still highly active, a feature of the region that is felt on a regular basis with significant earthquakes. The last major of these had an epicentre further north along this fault zone that struck with a magnitude 6.8 event in 1989 killing over 30,000 people. Understanding more about the timing of earthquakes could help our archaeological studies and thus we needed to find sites with long environmental records that were punctuated by features that showed the earthquake record. The delta on the northern river inlets gives just that kind of section with what appears to be a series of down-faulted land surfaces in a cyclic and fairly uniform sequence. This should provide just the kind of record we need for future detailed study.
|Tim at the Sevan section of repeat cycles|
Armenia has so much to offer in way of study sites both geologically and archaeologically. The people were great (especially thanks here to Drs Babajanyan and Pavel at the National Archaeological Inst), the food was great and the wine was great. Now for the big grant application to allow us to return to study the interplay between geology and archaeology.