Hot gates is a place that is closely linked to the famous Battle of Thermopylae. The place-name Thermopylae is referred to by Herodotus meaning “Hot Gates” named after the hot springs located at the mountain’s foothills.
The Battle is estimated to have taken place in September 480 BC between an alliance of ancient Greek city-states and the invading Persian army of Xerxes I. This pass, according to historians, was a very narrow strip of land between the steep slopes of Mount Kallidromon and the Malian Gulf Sea as you can see in the following picture.
Source: https://en.wikipedia.org/wiki/Battle_of_Thermopylae
Today the morphology of the area is very different to that of ancient times. Sedimentation and sea level drop drastically changed coastal morphology of the Thermopylae Pass over the past 2500 years. If you come to the place of famous battle, you will see a totally different scene.
Today the Thermopylae Pass is no longer a narrow pass between the mountains and the sea. The depositional process of the Sperchios River has filled a considerable part of the basin with alluvial sediments, resulting in the delta’s prolongation and the transformation of the narrow pass to a margin between the foothills of the mountainous terrain and the alluvial plain. The distance between the ancient battle terrain and the present shoreline is more than 5 km while the absolute elevations on the deltaic plain close to Thermopylae range between 2 – 1.5m asl. Also, the morphology of the ancient pass changed drastically due to the debris of small torrents forming alluvial fans along the edges of Mount Kallidromo and the Sperchios River plain. Finally, the travertine deposition in the vicinity of the hot springs is responsible for the present-day morphology (+9m asl.) of the battle terrain (also reffered as “Middle gate”) close to Kolonos Hill, where the final stage of the battle according to Herodotus took place.
https://www.tandfonline.com/doi/abs/10.3166/ga.23.241-253
All these information was proofed in years 2004-2005 when 20 boreholes were drilled during the subsoil survey due to the construction of the E75 motorway. This makes it possible to reconstruct the approximate shape of the Hot gates during the Battle of Thermopylae in 480 B.C.
Source: https://www.tandfonline.com/doi/abs/10.3166/ga.23.241-253
As you can see in the picture, at the site of the battle (near Kolonos Hill) the mainland was quite wide. However, its larger part was an impenetrable swamp that was constantly filled with water from the thermal spring. Based on the dating samples which are in very good coincidence with the proposed sea level curve for the North Aegean Sea, we can suggest that the alternations of the travertine deposits with the grey-green marshy sediments date to before 480 BC. The drillings’ spatial distribution in combination with stratigraphical data indicates that the width of the marsh should be more than 300 m.
Over the next millennia flow of geothermal water rich in calcium led to high depositional rates of travertine deposits (travertine sheets and ridges resembling a small fan) over a wide area.
The results of this geoarchaeological research showed that the battlefield in Thermopylae Pass was not a narrow passage between the mountain and the sea. Between the two there was a freshwater marsh supplied with large quantities of warm water coming from the thermal springs. The chronostratigraphical and sea level data confirmed its existence when the battle took place in 480 BC. The high accumulation rates of travertine deposits in the marsh created layers with a total thickness of approximately 13 meters in the last 2,500 years. Today the battlefield is a small hill with an elevation of 10m running beside waterways with continuous travertine deposition.
In 1935 a spa was built at the springs. Nowadays, it serves as a hostel for refugees from Africa. These refugees are friendly and there is no garbage in the area. Access to the springs is completely free.
The purpose of this Earthcache is to see for yourself how fast (at the age of the planet) this process is taking place.
Tasks (there is also third "BONUS" location):
- At the "waterfall" coordinates - estimate the height of the travertine deposit created by the hot waterfall.
- How long do you think it took to build this height of travertine deposit (under waterfall)?
- At the "spring" coordinates - Is the bottom of the pool the same as the bottom of the river near the waterfall? What is the difference?
- How would you explain the different increase in sediment height below the waterfall and across the plain.
- Add the picture of yourself or your personal item near the hot springs. (you can take a bath, it is free)
- (optional) – Go to another hot spring (few kilometers away) (WP) and add some pictures.