Petra "Lost City" of Jordan

The monastery at Petra, Jordan. There is a person in the doorway if you look really close, which shows the massive size of the construction (National Geographic, 2015).

The lost city of Petra! Sounds like something out of an Indiana Jones movie, which is funny since it was a film location for "Indiana Jones and the Last Crusade". Apart from the tourist destination and being a prime location for archaeological movies, Petra is fascinating for its water management techniques. The clever civilisation that lived in Petra and created all this were the Nabataeans. At their peak, the population was around 30,000 people which are a lot to cram into an arid city. 

Geology of the Area

The landscape in Petra, looks like a sea of yellow/orange and brown and made up of clay rocks and dust. The reason for the different colours is the composition. The oldest sandstone consists of coarse to medium grained quartz class, with an iron- and manganese-rich matrix. Below this layer of sandstone is a pre-Cambrian granite with gneiss and schists (Geotimes, 2004). The material exposed at the surface is primarily made up of different layers of sedimentary rocks that have been deposited throughout time. These layers are evident throughout the city as well as adjacent areas. The sandstones display old sand dune structures as well as cross-bedding and they have formed a steep, impressive canyon that leads you to the entrance of Petra, rather dramatically. According to (Geotimes, 2004) geologists have identifies the system as a braided river stream complex. There is then a friable, white sedimentary deposit on top of that and a limestone layer caps the high peaks of the region (Geotimes, 2004). The intricate water system of Petra helped buffer against erosion whereas surrounding the city wind and stream erosion deposits from the Holocene are evident (Geotimes, 2004).  
Petra sits on the western edge of the Arabian Plate to the south-east of the Dead Sea which can be seen in figure 1. There is a transform fault segment in the Dead Sea rift zone which the sandstone layers extend towards. Records show that there have been at least 20 major seismic events in the greater region. This is also evident in the city as there are fallen stone columns that line the main streets which relate to the earthquakes and aftershocks that overwhelmed the city in 363AD (Geotimes, 2004). The earthquake wrecked havoc in all areas to do with the city. Their water system crumbled due to displacement and movement caused by the fault. This lead to the surrounding sandstone being once again susceptible to weathering erosion. The flooding that created the canyon was a serious threat to the city at this time. Unfortunately, the shops that one lined the town are now filled with flood deposits, which tells you all you need to know (Geotimes, 2004). 

Figure 1: Google image of Petra in relation to the Red and the Dead Sea

Hydrology In Petra 

Throughout the city, there are a series of cisterns that held every drop of water that was rained down on them as well as water carried into the city by their "aqueducts" and pipes. I say aqueducts in quotation marks as they aren't the same as what we automatically think of like the Roman aqueduct bridges. These were channels dug into the side of hills in a downward gradient so the water flows down naturally, shown in figure 2. In some parts, there were covers over the channels to protect the water. The Nabataeans also created clay pipes that are tapered at the ends, something we have only figured out 200 years ago (Nabataea, 16/10/16). These pipes are a major advancement in their civilisation and can be seen in figure 3. 

Figure 2: Petra aqueducts dug into the side of the canyon walls.

(Wikimedia Commons, 2005)

Figure 3: Clay pipe with a tapered end

(Nabataea, 16/10/16)

By the sounds of it, Petra was a sprawling metropolis that had water irrigation for gardens and an advanced water system that allowed for a large population to survive in an arid climate. The softer rock in the mountains allowed for the Nabataeans to carve out caves that were either used for tombs or a place to get out of the blazing heat. Everything seemed to be going great but unfortunately, all good things must come to an end. 

Demise Of Petra and How It Was Rediscovered

On May 19th 363 AD, a massive earthquake occurred that according to a letter wrote by a Jerusalem bishop, destroyed half of Petra. Ultimately, one would think this could be the cause of the demise of the Nabataeans but there has been evidence found that this civilisation survived at least 300 years or so after the fault rupture (Smithsonian, 2007). The evidence is in the construction of new buildings just across the main street to the Great Temple. In one of the post-earthquake churches, they found evidence that a vibrant civilisation lasted until at least seventh century A.D, after which pretty much the whole city was abandoned. This is a completely different outcome to what I had put my bets on given the marine flood sediments found throughout the city. 

The city was then completely abandoned for at least 100 years until it reemerged in the 19th century as a tourist destination for western travellers (Smithsonian, 2007).  

References

Geotimes, 2004, Petra: An Eroding Ancient City, viewed: 16/10/2016, http://www.geotimes.org/june04/feature_petra.html

Nabataea, Petra Water Works, viewed: 16/10/2016, http://nabataea.net/waterw.html

National Geographic, 2015, "Lost City" of Petra Still Has Secrets to Reveal, viewed 16/10/2016, http://science.nationalgeographic.com/science/archaeology/lost-city-petra/

Smithsonian, 2007, Reconstructing Petra, viewed: 16/10/2016, http://www.smithsonianmag.com/history/reconstructing-petra-155444564/?no-ist=&page=2

Wikimedia Commons, 2005, Petra Aqueduct, viewed:  16/10/2016, https://commons.wikimedia.org/wiki/File:Petra.aqueduct.jpg

Bibliography and Recommended Reading

http://www.smithsonianmag.com/history/reconstructing-petra-155444564/?no-ist=&page=2

-This website has a lot of awesome information on how the Nabataeans lived and funnily enough, about the real estate back in the day. 

http://rsta.royalsocietypublishing.org/content/368/1931/5249

The Netherlands

Delta Works in the Netherlands to help prevent storm surges and floods.
(Holland, 16/10/16)

There is an old Dutch saying that goes "While god created the Earth, the Dutch created the Netherlands"(Rosenberg, M., 2015). The dutch are an interesting people with a unique culture, language and way of life. But the single most interesting thing about them is their ability to overcome nature and successfully retake land back from the ocean.

A Small History Lesson

Around 400 BCE the first settlers to the Netherlands were the Frisians. They created what they called terpen. This was one of their terms for villages and what it meant was series of houses built on earth mounds to elevated them from the risk of floods. These terpen still exist in the Netherlands today. Small dikes were built around the terpens to add more protection. Unfortunately on December 14th, 1287, this protection did nothing against the North Sea as it flooded the area, killing over 50,000 people (Rosenberg, 2015). 

If you want more information about this, go to the website below:

http://geography.about.com/od/specificplacesofinterest/a/dykes.htm

It wouldn't be wrong to say the Netherlands are one of the most innovative countries in the world. They simply have had to be, to survive. A quote from the Netherlands Ambassador really backs this statement up, saying;

“It’s no exaggeration to say that innovation is in our DNA. We’re always willing to try new things, to find a better way to do something, and if something doesn’t work, we’ll keep trying until we find something that does. If necessity is the mother of invention, then the Netherlands is the father of innovation.” (Holland, 16/10/16).

Geology Of The Area

The geology of the Netherlands is quite intricate due to a number of times it has been underwater, only to be brought back to the surface again. It is also hard to say when the Netherlands became as we know them today, which is why it is broken up into three periods; the Paleozoic, the Mesozoic and the Cenozoic (Deltawerken, 2004). 

Paleozoic - The oldest rocks, which can be found in the Heimans Quarry, originate from the Carboniferous period. In the north and south of the Netherlands, this strata layer lies 4 km below the surface. This layer is no longer found above ground now due to erosion (Deltawerken, 2004). The next layer on top is comprised largely of sandstone and has natural gas reserves. This layer is around 250 Mya (Million years ago). 

Mesozoic - The following rocks were all created during this time period;  sandstone, evaporates (which are sediments that were created through of evaporation of water), chalk, dolomite, shale and gypsum (Deltawerken, 2004). Due to erosion, the majority of all the shale has now disappeared. During the Jurassic period, rocks that could contain petroleum were formed. In the Cretaceous period, the meteorite which hit the Yucatan peninsula caused an average warming of the oceans by 10 degrees celsius. Also during this time, the Netherlands were completely submerged by the ocean, which resulted in the formation of the chalk (Deltawerken, 2004).  This is also most likely when the gypsum and dolomite were formed as they need marine environments to deposit. 

Cenozoic - As we enter this time period, more layers are accumulating. The next one is the clay layers that originated in the Oligocene. After that comes the Miocene where quartz and coal were formed in the eastern part of the Netherlands (Deltawerken, 2004). Now comes the ice ages. The first one was during the Elsterien period which didn't really do much except cover the Netherlands completely in ice. The second one, however, changed the landscapes radically in the Saalien period. This was due to the deposition of lateral moraine and boulder clay. Massive boulders were transported all around the country which inevitably in the 2000BC were used to build megalithic tombs. These are above ground tombs that are made of boulders in which the dead reside. They look as rustic as it sounds, take a look at figure 1. But this is how the Stone Henges originated. 

Figure 1: Megalithic Tombs in the Netherlands
http://thefairytaletraveler.com/2014/05/15/europe-megalithic-route/

Holocene - For the last 10,000 years the Netherlands have mainly been influenced by sea level rise and Human involvement. 

How The Hydrosphere Is Influenced

The Netherlands are dominated by human construction in an attempt to reclaim stolen land from the sea. Most of the western half of the Netherlands is below sea level (shown in figure 2) and the eastern section comprises of shallow and deep aquifers. Vries (2007) states that the western area of the Netherlands is like a "patchwork of polders, each with its own set of an artificially controlled level of surface water and groundwater." Polders are tracts of low-lying land that have been reclaimed by the land. They are surrounded by dykes to protect it from flooding or attempts from the sea to take the land back. Vries (2007) then goes on to state that the total number of 1700 million m3 of fresh water is annually extracted in the Netherlands and of that amount, 60% of this is used for public water supply. Across the Netherlands, the water table varies like all other systems but it is extremely shallow in certain parts. The groundwater is present in the pores and fractures of the sedimentary rocks on and off the shore.  

Figure 2: Surface topography of the Netherlands; elevation relative to NAP (= Normaal Amsterdams Peil = Dutch ordnance datum, approximate average sea level) (Vries, 2007).

The Dutch have innovative agriculture and agrifood sectors. They have constructed greenhouses that "float" on the water! This is shown in figure 3 below and all I can say is, imagine watching a storm in that building! But in all seriousness, the Dutch manage to deliver vegetables to the New York streets on the same day they were harvested in the Netherlands (Holland, 16/10/16). 

Figure 3: Floating Greenhouse in Naaldwijk (Holland, 16/10/16).

I guess the point to this post is that there is always an answer to everything if you are Dutch? The innovation and determination of the people of the Netherlands are highly admirable. 

References

Deltawerken, 2004, Geology of the Netherlands, viewed: 16/10/2016, http://www.deltawerken.com/Geology-of-the-Netherlands/112.html

de Vries, J.J., 2007, 'Geology of the Netherlands', Royal Netherlands Academy of Arts and Sciences, 295-315. 

Holland, The Netherlands: Fertile ground for innovation, viewed: 16/10/2016, http://nlintheusa.com/fertile-ground-for-innovation/

Rosenberg, M., 2015, Polders and Dikes of the Netherlands, viewed: 16/10/2016, http://geography.about.com/od/specificplacesofinterest/a/dykes.htm

Bibliography and Recommended Reading

http://www.hydrology.nl/images/docs/dutch/key/Groundwater_De_Vries.pdf