GEOLOGY [ the 14 th of December field trip] Table of contents……………………………………………….. Introduction…………………………………………… ………….. The road trip and the on foot journey………………… The geological history of the area………………………. Distinguishing between the rocks………………………. The different types of rocks………………………………. Can I build in this area………………………………………. Water and sedimentary rocks…………………………… Dames in general/Dames in Jordan …………………. The Al-Mujib dam/History……………………………….. 1 | P a g e -geology of the area ………………………………………….. - construction…………………………………………… ………. -goals ……………………………………………………………… . Conclusion……………………………………………… ……….. Introduction: We have traveled south of Madaba down to the north of Al-Karak heading to Al-Mujib dam as our final stop. I will list all of the information we have learned about the area in sequential order starting from the knowledge we have gained through our walk along the sideway rocks down to the Al- Mujib dame. The road trip and the on foot short journey: 2 | P a g e On our way we had few stops to study and examine the rocks on the sides of the road. First we have noticed that it is both a mountainous and a valley constructed area [with about 800-1000m difference in elevation] and that is due to the rapid sea weathering and deposition of sediments throughout the pervious ears when the area was the floor of the ancient Tethys ocean. The geological history of the area : The Tethys Ocean is the ancient body of water that separated Gondwana and Lorassya’s cotenants from each other. Jordan is a part of the Arabian plate that was at the time united with the African plate and together they shaped Gondwana’s cotenant. During the upper cretaceous period Jordan was immersed under the Tethys Ocean as it flooded [about 100 million to 40 million years], which resulted in the wide spread of sedimentary rocks in the area. The water of the ancient ocean deposited sediments of both Gypsum and Marl rocks. Furthermore, as the water flow, where 3 | P a g e Jordan was, used to be abundant with Phosphor, Silica and other biological matters which resulted in the precipitation of Phosphates, Limestone and Oil Shale. Distinguishing between the rocks: Looking closely at the high terrains on the sides of the road we can easily notice the inter- bedding structure and the conformable layers of rocks on top of each other. This is strong evidence that these rocks are sedimentary. The alternating beds happen to be Limestone and Chert. We can tell the difference between both as [Limestone reacts with weak acids such as HCl quite fast. However, since Chert consists of quarts it is considered to be relatively hard and resistant to abrasion according to Moh’s scale (as quarts fall on the 7 th stage) meaning that it is tough.]This continuous for about 60-7m . Walking farther south, Dolomite can also be found, and that is a very interesting note as this type of sedimentary rocks is highly organized in nature and can’t be easily deposited; unless the water responsible for the 4 | P a g e precipitation is abundant with CaCO3 and MgCO3. We can distinguish between Dolomite and the other rocks present in the area with either using the HCl weak acid [as Dolomite slowly reacts unlike limestone, whereas Chert doesn’t react at all]. Or by taking a thin cut of it and studying it under the microscope. One can also catch sight of both biological and evaporate sedimentary rocks along the road to Al-Mujib dam such as Coquina [silica cemented] and Gypsum rock. White outcrop the leaves white powder trace on the hands is found as well and happens to be Chalk rock [a type of Limestone]. Different types of rock, what does this tells us : The presence of different types of sedimentary rocks and the horizontal layers is due to the various lithifications and gravity depositions throughout the years. [Proving that the area was part of the ocean floor of the ancient Tethys]. Can I build on these rocks: 5 | P a g e Moreover, this structure of conformable layers of sedimentary rocks can handle high compressions thus making it suitable for construction purposes .However, the existence of fault in these layers [due to tectonic forces] that cause the rocks to either break along a plain or for pleating to occur; creates instability and a visible change in the type of rocks present along the same line which is a very important factor to study when intending to construct various engineering projects. Water and sedimentary rocks: Permeability is high and the faults forming numerous joints have resulted in high secondary porosity so, both allow the water to pass through the layers and move freely within [Aquifers permeable rock or sediment that transmits groundwater freely]. However, since the total volume of pore spaces in these rocks is almost zero; it cannot hold liquids making it not so good of a reservoir of underground water. 6 | P a g e Dames in general: Dames: are barriers that impound water or underground streams. These huge projects are constructed for various reasons and for various goals in mind. Such as: 7 | P a g e Millions of people depend on dams to help provide the right amount of water. Most dams do more than one job! We fish, swim and boat on about 1 in every three lakes formed by dams. Lots of dams provide water for growing crops and for farm animals to drink. Dams also give us hydroelectric power! For generating electricity Dames in Jordan:that is friendly to the environment. We have ten main dams in Jordan, they are [Al-Walah, Al-Wehdah, Wadi Al-Arab, Sharhabeel; Al-karamh, Al-kfrain, Shea’b, Al- Mujib and Al-Tanour] dams, with a total storage capacity of 325 million cubic meters of water. Al-Mujib dam: 8 | P a g e In the following pages I will discuss Al-Mujib dam specifically, since we have visited it and got to know the area better. It is located about 35kms south of Madaba and north of the city of Al-Karak.[About 100 km south of the capital Amman]. History: Back in 1995 the idea for the [Intergrated project of the southern valleys] was accepted by the [Jordanian valley authority] . The project states that three dams including Al-Mujib dam be constructed in the upsream of the Dead sea area to collect the running water. Buliding of the dam started in the year of 1999 and was finished in 2003. With a total storage capacity of 31 million cubic meter. For various objectives in mind: For drinking purposes for the capital Amman . For chemical industry usage and the Potassum factory With the intention of devoloping the area specially with having the Al-Mujib biosphere resirve near. 9 | P a g e The geology of the area: The nature of the geology of the location of the dam consists mainly of Limestone and Marle [as mentioned earlier these rocks have high permability and zero poresty] making it sutable for water to pass thorough it and can easly menuver within. Making the Al-Mujib dam a recharger for the underground water of the area. NOTE: During the early years of construction geologists noticed a somesort of unstability in the eastren area [that may cause dangerous landslides in the future] and thus advised enginreers to not use that zone as a base for their work . That is why a 20 degree deflection to the right is present in the final body of the dam. Before starting on the constrution of any dam few aspects should be taken into consideration: The impotantce of studying the valley where the builiding will take place. [resulted in the deflection in the body of 10 | P a g e the dam to avoid any serious accedents in the future] Getting to know the catchment area.[for the Mujib vally is 39000 m square of deserted area] Listing the goals for constructing.[drinking , manufacturing and to revive the area] Measurments of the dam : With the concern that the volume of the water reserved in the dam will cause much Dam type RCC main body and compression dam abutment pressures RCC [in Height 62m the middle body of the dam] was Length 765m advised for usage as it can withstand Storage 31 million cubic meter pressure and for The rest of the detailed measurements can be found in the paper we got from the dam control office and I only listed the measurements I found most important 11 | P a g e Has the dame achieved its’ intended goals? The Al-Mujib dam did not only achieve its’ initial intended goals, but also succeeded in developing the area; as this huge body of water became a stop for numerous types of migratory birds reviving the Muijb biosphere reserve. In addition to that, the water collected in the dam is suitable not only to use for manufacturing purposes and machines but also for drinking. As in January of 2015, a project will be implemented to pump 5 million cubic meters of water to Al-Karak city for drinking purposes. NOTE: The project of pumping water from the Dam will cost much less than getting water from Al-Desah to Karak. Problems: One of the problems that face the workers on the dam is the huge amount of sediments that accumulate at the bottom of the water tank. About 3 MCM of fragments are present. However, to get rid of these accumulates 12 | P a g e opening the gates [Bottom outlets] and flushing out the water would be the solution. But this would mean that there will be about 52 CM per second discharge of water, causing us to lose much of the commodity, Jordan suffers scarcity of [Water].