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Toompea - EarthCache

A cache by Coland Send Message to Owner Message this owner
Hidden : 12/11/2015
Difficulty:
2 out of 5
Terrain:
2 out of 5

Size: Size:   other (other)

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[Est]

Toompea - EarthCache

Toompea

Toompea on lubjakivi mäe keskosas Tallinna linn , Eesti pealinnas. Mäge on piklik platoo, mis mõõdab umbes 400 250 m, pindala 7 ha (17 aakrit) ja on umbes 20-30 meetrit kõrgem kui ümbritsevatel aladel . Toompea on osa Tallinna vanalinna UNESCO maailmapärandi nimistusse.

Geoloogia Toompea

Tallinna piirkonnas ja kogu Põhja-Eesti Proterosoikum aluskorra on kaetud Upper Proterosoikum ja Alam-Paleosoikumi settekivimite, kuni madalaima Ülem-Ordoviitsium (mõned 456000000 aastat tagasi) lähedal Põhja-Eesti klint. Klint vormid umbes veerandi tohutu Balti klint, paekivist astang ulatub 1200 km kaugusel Laadoga Venemaal Ölandi saarelt Rootsis. Ülemine piir keldris on sügavusel 130-150 m allpool merepinda. Kiht settekivimite moodustavad pealispinna keldris on õrn lõuna kalle, keskmiselt 3-4 m kilomeetri kohta. On põhjal litoloogia settekivimite, Alam-Paleosoikumi Tallinnas saab jagada kahte ossa: kõrgeimas Neoproterosoikum (Ediacaran, varem Vendi), Alam ja Ülem-Kambrium (Furong) ja Alam-Ordoviitsiumi (Tremadoci), mis koosneb peamiselt mandritekkelistest kivid; ja ülemine osa Alam-Ordoviitsiumi alumise osa Ülem-Ordoviitsium (Arenig madalaima Caradoc), mis moodustati peamiselt karbonaadi ja peeneks mandritekkelistest kivid.

Linna piires, topograafia aluspõhja iseloomustab mitu suhteliselt väike positiivne - Toompea, Sõjamägi - ja enam nähtavaks negatiivsed küljed - kolm orud kuni 140 m sügav täis kvaternaarisetetest. Topograafia aluspõhja on keeruline tekke tõttu panuse erinevate leevendust moodustavate jõud. Kõige olulisem tegur on heterogeenne lithological koosseisu (st ebavõrdne vastupanu kivimite denudational protsessid).

Järsk astang, Põhja-Eesti klindi, on silmapaistvaim aluspõhja reljeef kujul. Areng klint algas suure tõenäosusega ajal Cenozoic. See oli moodustunud paljanduvad ajal pikema mandri jooksul. Hiljem muutus see jää erosiooni ja mere hõõrdumist vastavalt kõvadusega kivimite. Klint tekkinud vesi Läänemere ajal Yoldia regressiooni, mõned 10.300 kuni 9500 aastat BP. Alumine valdkondades tänapäeva sai linn kuiva hiljem, vastavalt tühistamise merele. Klint koosneb kivimitest ebavõrdse vastupanu. Lõik on Suhkrumäe kuvab puhas kõva lubjakivi ja dolokividest tipmine 6,5 m. Paekivi ja dolokividest on underlain pehme Furong-Alam-Ordoviitsium mandritekkelistest kivid, peamiselt liivakivid.


 

1 - Lower sinisavi, 2 - Alam- savi, 3 - Ülem- Kambriumi - Alam-Ordoviitsium liivakivid, 4 - Alam-Ordoviitsium argillites, 5 - Lower - Kesk-Ordoviitsiumi lubjakivi, 6 - Kesk-Ordoviitsiumi lubjakivi , 7 - Lähis - Ülem-Ordoviitsium lubjakivid kukersiit 8 - Ülem- Ordoviitsiumi savikas lubjakivi koos mergleid, 9 - Põhja- Eesti ( Balti ) klint.

 

Tähtsaim kihid Toompeal (480 220 m; ELEV. 47,5 m) kuuluvad madalaim Uhaku lade. See stratigraphic tase on veidi kõrgem kui tähtsaim lubjakivi voodid Suhkrumäe, kus klint on suurim piiresse linna, tõuseb kuni 47 m üle merepinna. In võõrväärtussubjekt Toompeal denudational jäänuk Toompeal (ilmselt eelnevalt kvaternaari ajastu), Alam-ja Kesk-Ordoviitsiumi kihid on veidi lõuna dip (0º15 ") iseloomulik kogu Alam-Paleosoikumi kivimitest Eestis. Kuid väike paljand selles kohas, mõned kõrgeimas lubjakivikihtide deformeeruvad, mille dip 5 kuni 10 kraadi. Samal koht seitse väikest nihestused kärpida amplituudiga 15 kuni 60 cm, kõik 2,2 m. Dislocations lihtne näha, sest nad järgivad kihtides Aseri Oolitic lubjakivi. Lõhed kuni 25 cm laiused täis Pleistotseeni setete (Kuni), mis annab aimu nende glaciotectonic laadi.

Toompea esimene kujunenud saare Balti jääpaisjärve umbes 10.000 aastat tagasi. Tänu stabiilsele postglatsiaalsete tagasilöögi sai see ühendatud mandriga esimestel Litoriinamere staadiumis. 5000 eKr mere veel jõudnud jalamil kaljud Toompea. Kaasaegne rannajoon on kaugemal kui 1 km kaugusel Toompea ja Toomemäe asub 17-20 m üle merepinna. Mäe jõuab umbes 48 meetrit (157 jalga) kõrguse.

Lubjakivi

Lubjakivi on settekivim, mis koosneb suuresti mineraalid kaltsiit ja aragoniit, mis erinevad kristallvormidele kaltsiumkarbonaati (CaCO3). Enamik lubjakivi koosneb skeleti fragmente mereorganismide nagu korall, forams ja molluskid.
Lubjakivi moodustab umbes 10% kogumahust kõigi settekivimid. Lahustuvus lubjakivi vee ja nõrga happe lahendusi viib Karst maastikud, kus vesi hajub lubjakivi üle tuhandeid miljoneid aastaid. Enamik koobas süsteemid on läbi lubjakivi aluspõhja.
Lubjakivi kasutatakse paljudel: kui ehitusmaterjali, nagu koondtuluna aluse teede, nagu valge pigment või täidisena tooted nagu hambapasta või värvide ja keemilise toorainena lubi.

Settekivim

Settekivimid tüüpi kivi, mis on moodustatud ladestumist materjali Maa pinnal ja sees veekogud. Settekivimid on leitud ka Marsil. Settimine on üldnimetus protsesse, mis põhjustavad mineraalide ja / või orgaanilised osakesed (detriit) elama ja kuhjuvad ja mineraalid, et sadestada lahusest. Osakesed, mis moodustavad settekivim, kogudes nimetatakse setete. Enne hoiule, setete moodustasid murenemise ja erosiooni allikas ala ja seejärel transporditakse kohale ladestumist vesi, tuul, jää, mass liikumise või liustikud, mida nimetatakse aineid paljanduvad.
Kivimis kaas kontinendil maakoores on ulatuslik, kuid kokku panus settekivimid on hinnanguliselt ainult 8% kogumahust kooriku. Settekivimid on vaid õhuke spoon üle maakoor koosneb peamiselt tard- ja moondekivimid. Settekivimid ladestuvad kihtidest kihtides, mis moodustavad struktuuri nimetatakse voodipesu. Uuring settekivimid ja kivimikihiga annab informatsiooni maapõue, mis on kasulik tsiviilehitus, näiteks teede, majade, tunnelid, kanalid või muud struktuurid. Settekivimid, on samuti olulised loodusvarade nagu kivisüsi, fossiilkütuste, joogivee või maagid.

EarthCache

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Küsimused:

1. Kirjeldage lubjakivi kohas (nt värv, tekstuur tera suurus jne). Kas paekivi on isegi värvi või on laigud, mis erineb palju ümbritsevast lubjakivi?

2. Kuidas sa saad olla kindel, et see on paekivist, et leiad mõõdus? Selgitage.

3. Kirjeldage kihtide lubjakivi. Kas nad on võrdselt paks? Kas sa arvad, et nad on sama tugev? Selgitage.

4. Valikuline: Saada pilt sinust ja/või su GPSr kohas oma log. See on täiesti vabatahtlik ja ei ole metsaraie nõue.

 

[Eng]

Toompea - EarthCache

Toompea

Toompea is a limestone hill in the central part of the city of Tallinn, the capital of Estonia. The hill is an oblong tableland, which measures about 400 by 250 metres, has an area of 7 hectares (17 acres) and is about 20–30 metres higher than the surrounding areas. Toompea is part of the Tallinn Old Town UNESCO World Heritage Site.

The Geology of Toompea

In the Tallinn area and throughout northern Estonia, the Proterozoic crystalline basement is cov­e­red with Upper Proterozoic and Lower Paleozoic sedimentary rocks, up to the lowest Upper Ordovician (some 456 million years ago) near the North Estonian Klint. The klint forms about a quarter of the huge Baltic Klint, a limestone escarpment stretching 1,200 km from Lake Ladoga in Russia to Öland Island in Sweden. The upper boundary of the basement is at a depth of 130 to 150 m below sea level. The layer of sedimentary rock forming the upper surface of the basement has a gentle southward inclination, on average 3 to 4 m per kilometer. On the basis of the lithology of the sedimentary rocks, the Lower Paleozoic in Tallinn can be divided into two main parts: the uppermost Neoproterozoic (Ediacaran, earlier Vendian), Lower and Upper Cambrian (Furongian) and the Lower Ordovician (Tremadocian), composed mostly of terrigenous rocks; and the upper part of the Lower Ordovician to the lower part of Upper Ordovician (Arenig to lowest Caradoc), formed mainly by carbonate and fine-terri­genous rocks.

Within the town, the topography of the bedrock is characterized by several relatively small positive – Toompea, Sõjamägi – and no longer visi­ble negative features – three valleys up to 140 m deep filled with Quaternary sediments. The topography of the bedrock is of complicated genesis because of the contribution of different relief-forming forces. The most important factor is the heterogeneous lithological composition (i.e., unequal resistance of the rocks to denudational processes).

A steep escarpment, the North Estonian Klint, is the most notable bedrock relief form. The development of the klint started, in all likelihood, du­ring the Cenozoic. It was formed by denudation during a prolonged continental period. Later on, it was transformed by glacial erosion and marine abrasion according to the hardness of the rocks. The klint emerged from the waters of the Baltic Sea during the Yoldia regression, some 10,300 to 9,500 years BP. The lower areas of the present-day town became dry land later, according to the withdrawal of the sea. The klint consists of rocks with unequal resistance. The section at Suhkrumägi displays pure hard limestones and dolostones in the topmost 6.5 m. The limestones and dolostones are underlain by soft Furongian–Lower Ordovician terrigenous rocks, mainly sandstones.

1 – Lower Cambrian sandstones, 2 – Lower Cambrian clays, 3 – Upper Cambrian–Lower Ordovician sandstones, 4 – Lower Ordovician argillites, 5 – Lower–Middle Ordovician limestones, 6 – Middle Ordovician limestones, 7 – Middle–Upper Ordovician limestones with kukersite, 8 – Upper Ordovician argillaceous limestones with marls, 9 – North Estonian (Baltic) Klint.

 

The topmost layers on Toompea Hill (480 by 220 m; elev. 47.5 m) belong to the lowest Uhaku Stage. This stratigraphic level is a little higher than the topmost limestone beds at Suhkrumägi, where the klint is at its highest in the limits of the town, rising up to 47 m above sea level. In the outlier Toompea, the denudational relic of Toompea Hill (probably of pre-Quaternary age), the Lower and Middle Ordovician layers have a slight southward dip (0º15’) typical of all the Lower Paleozoic rocks of Estonia. However, in the small outcrop at this site, some of the uppermost limestone layers are deformed, having a dip of 5 to 10 degrees. At the same place seven small dislocations crop out with an amplitude of 15 to 60 cm, in all 2.2 m. The dislocations are easy to see, as they follow the layers of the Aseri oolitic limestone. Fissures up to 25 cm wide are filled with Pleistocene sediments (till), which gives an idea about their glaciotectonic nature.

Toompea first emerged as an island from the Baltic Ice Lake around 10,000 years ago. Due to steady post-glacial rebound it became connected with the mainland during the early Littorina Sea stage. At 5,000 BCE the sea still reached the foot of the cliffs of Toompea. The modern coastline is at a distance of more than 1 km from Toompea and the foot of the hill lies at 17–20 m above sea level. The hill reaches about 48 metres (157 ft) in elevation.

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Most limestone is composed of skeletal fragments of marine organisms such as coral, forams and molluscs.

Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock.

Limestone has numerous uses: as a building material, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, and as a chemical feedstock for the production of lime.

Sedimentary rock

Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentary rocks have also been found on Mars. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation.

The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other structures. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores.

This EarthCache

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The questions:

1. Describe the limestone at the site (e.g. colour, texture grainsize etc.). Does the limestone have an even colour or are there spots which differs a lot from the surrounding limestone?

2. How can you be sure that it is limestone that you will find at the size? Explain.

3. Describe the layers in the limestone. Are they equally thick? Do you think that they are equally strong? Explain.

4. Optional: Upload a picture of you and/or your GPSr at the site to your log. This is completely optional and is not a logging requirement.

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