Theoretical introduction
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated, although there are exceptions. In geology, the term "marble" refers to metamorphosed limestone, but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material.
The Greeks, Romans, and Byzantines largely used marbles for buildings and monuments and transported huge quantities of marble from ancient Mediterranean quarries to most Near Eastern archaeological sites. At most cities of the Decapolis League in northern Jordan, the marble was used widely for statues, architectural elements and decorations.
Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.
The green marble is a low-grade foliated metamorphic rock, an impure marble derived from marly limestone and composed mainly of calcite and subordinately of quartz separated by veins of muscovite, plagioclase and chlorite parallel to foliation
Gadara
The ruins of ancient Gadara (one of the Decapolis cities) represent successive cultures starting from the Greek and ending with the Ottoman. In 323 B.C., Gadara became part of Ptolemy’s dynasty in Egypt, but in 63 B.C., it was captured by Gnaeus Pompeius, the Roman general. Around the 7th and 8th centuries A.D., most of the city buildings were destroyed by earthquakes and Gadara was then abandoned. The high-quality marble used in Gadara was quarried in large blocks, while Jordan’s marble is of poor quality and fractured, so it cannot be quarried the same way.
Nymphaeum
A nymphaeum in ancient Greece and Rome, was a monument consecrated to the nymphs, especially those of springs.
The nymphaeum in Umm Qais, probably built in the second half of the 2nd century AD, stands on the northern end of the Decumanus Maximus, exactly opposite the western terrace. The 15 m wide monumental public fountain was originally two-story and decorated with sculptures.
In 1998 a marble block with an inscription was found in a wall a little further along the main street. It indicates that the nymphaeum with marble statues was donated by a certain Aurelios Diophantus, who held the position of Astynomos (high police officer, city supervisor, or law enforcement officer).
Tasks
At the coordinates you'll find the ruins of Nymphaeum. It contains several types of marbles, but you'll be interested in the column. Half of the column is still standing and the other half is lying near coordinates.
To log this Earth Cache, please answer the following questions using personal message:
- From what type of marble is this column made of? You don't have to say the exact type of marble, but I want you to name it color type. Here are some types of marbles that can be found in Gadara: light/dark grey, white with red/brown/black bands, beige, ruby red, green.
- Can you see layers in that marble or are they undistinguishable?
- On the left side of the fallen column (where should be the top if it would be standing) you can see some crystal incursion. What is the color and size of that incursion? Can you see other incursions in the column?
- Make a photo of you/your GPS/nick/personal item in Umm Qais with any marble object OTHER THAN the column from listing. Attach the photo to the log.
- Optional: If you could get a sculpture from any marble - what color would it be? Write the answer in log.
You can log this EC right after sending me answers. You don't have to wait for my response. I'll contact you if there'll be any problem.