Cwm Rhondda EarthCache
Hidden : 10/29/2009
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size: other (other)

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Geocache Description:

The VIEW POINT is not the cache site! THIS IS INTENDED AS ONE OF A SERIES OF AN 'ASSESSIBLE' EARTHCACHES.

This earth cache is glacial 'cirque'.

Look left (north-east) to the cirque also is known as a coombe or coomb in England, a combe or comb in the US, a corrie in Scotland and Ireland, and a cwm in Wales (You can reset your GPSr to N51.39.208 and W003.33.368 to point directly into the basin) This cwm is a landform found among mountains as a result of alpine glaciers. They may be up to a square kilometre in size, situated high on a mountainside near the firn line, and typically are partially surrounded on three sides by steep cliffs.



The highest cliff often is called a headwall. The fourth side is the "lip," the side at which the glacier flowed away from the cirque. Many glacial cirques contain tarns dammed by either till (debris) or a bedrock threshold. When enough snow accumulates it can flow out the opening of the bowl and form valley glaciers which may be several kilometres long.

Cwms like this form in conditions which are favourable. In the northern hemisphere the conditions include the north-east slope where they are protected from the majority of the sun’s energy and from the prevailing winds. These areas are sheltered from heat, encouraging the accumulation of snow; if the accumulation of snow increases, the snow turns into glacial ice. The process of nivation follows, whereby a hollow in a slope may be enlarged by freeze-thaw weathering and glacial erosion. The freeze-thaw cycle erodes at the lower rocks and causes it to disintegrate, which may result in an avalanche bringing down more snow and rock to add to the growing glacier.

Eventually, this hollow became large enough that glacial erosion intensifies. Debris (or till) in the ice also may abrade (glacial abrasion) the bed surface; should ice move down a slope it would have a ‘sandpaper effect’ on the bedrock beneath, on which it scrapes. Eventually, the hollow may become a large bowl shape in the side of the mountain, with the headwall being weathered by constant freezing and thawing, and as well as being eroded by plucking.

The basin will become deeper if it continues to become eroded by abrasion. Should plucking and abrasion continue, the dimensions of the cirque will increase, but the proportion of the landform would remain roughly the same. However this Cwm has a feature which is common to South Wales (Question 1c) The landscape of the area was altered during the Pleistocene period, approximately 18,000 years ago, by glaciation to create the landscape we know today. The principle glacial collecting point in South Wales was the Carmarthenshire Fans and the Brecon Beacons, the northern face of which was the source of numerous corrie glaciers.

The Pennant escarpment and Craig-y-Llyn was the only barrier effectively to deflect the main Fans-Beacons ice-flow and created an icecap of its own. It was this force of ice, which modified the Rhondda Valleys, producing typical glacial features, such as the corries or glacial cymoedd visible today at Cwmsaerbren and Cwmparc.

Please EMAIL OR MESSAGE the answers ~ From the guidelines: You do not need to wait for permission to log. Requiring someone to wait is not supported by the EarthCache guidelines. You should send your logging task answers , then log the EarthCache.

When I review your logging task answers, if there is a problem, I will contact you to resolve it. If there is no problem, then your log simply stands.Please do not include the answers in your log even in an encrypted form.

FROM THE FIRST VIEWPOINT

1 (a) How wide would you estimate the Graig Fawr Cwm to be? (b). How far from bottom of the basin to the first houses in Cwmparc? (c) So is the Cwm wider than it is long?

2. Estimate the pitch of the north-west wall, in degrees. ( 90˚ being vertical and 0˚ being flat )

3. There is farm gate at this first viewpoint . How many horizontal, diagonal and vertical bars are there? Please don't post any pictures!

FROM THE SECOND VIEWPOINT 51.38.419 003 32.047

4. There is an information board. Name the painter and painting illustrated?

Post a picture if you want, but don't put anything into the photo that would allow someone else to read the info. board.

ADDITIONAL INFORMATION ABOUT THE AREA.

The historic landscape area of the Rhondda is located within the dissected plateau of the upland region of Glamorgan, the Blaenau Morgannwg. The northern part comprises the Craig-y-Llyn escarpment of Pennant Sandstone. Central to this area is the prominence of Carn Moesen (600m) from which three flat-topped ridges extend towards the southeast, enclosing the deep river valleys of the Rhondda Fawr and Rhondda Fach.

To the east Cefn Gwyngul and Carn-y-Pigwn (470m) enclose the Rhondda Fach from the Cynon river system.. The sources of the two Rhondda Rivers lie on Carn Moesen and Mynydd Beili-glas at the north of the area. They converge at Porth to form the Afon Rhondda, which eventually empties into the Taff at Pontypridd. Pollen analysis from the Bronze Age burial cairn on Crug-yr-Afan, near Cwmparc, indicates a contemporary environment of heathland, with an open tree cover dominated by oak. Evidence suggests that by the end of the Bronze Age, the upland areas of the Rhondda, like most of the uplands were covered by extensive blanket peat.The historic landscape area is situated within the South Wales Coalfield; the geology of which belongs to the Carboniferous System.

The Rhondda Valleys are located within the Coal Measures near the middle of the Carboniferous syncline. Secondary upfolds or anticlines, running approximately east-west, have complicated the geology of the area and acted to bring the numerous coal seams of the area nearer to the surface. When the geological conditions of the area were discovered during the mid-nineteenth century, the Rhondda Coalfield was rapidly developed, and the coal industry of the region, previously restricted to the Lower Rhondda, was extended into both valleys.The Coal Measures comprise three series; the Upper Coal, Pennant and Lower Coal Series, only the latter two occur in the Rhondda Valleys.

The Pennant Series comprises sandstones and grits, known commonly as Pennant Sandstone; the shales belonging to this series are less significant in the Rhondda, though the series does contain two seams of bituminous coal, suitable for heating and the production of gas, No. 1 and No. 2 Rhondda Seams. The Lower Coal Series includes all the high-grade bituminous and steam coals, on which the fame of the Rhondda was ultimately built. Rhondda No. 3, the highest seam of the series, was essentially a domestic and coking fuel. It was the deeper steam coals, with their high carbon and calorific content and smokeless nature, however, which were the prime objectives of the coal industry.

The steam coal seams comprised the Abergorchi, the Hafod, the Pentre, the Gorllwyn, and the deeper, Two-Feet-Nine, the Four Feet, the Six Feet, the Red Vein, the Nine Feet, the Bute, the Five Feet, and the Gellideg. (Incidentally,

Cwm Rhondda, the Welsh name for the Rhondda Valley, and is also a popular hymn tune written by John Hughes (1873-1932), and often erroneously called Bread Of Heaven.)



There are some traditional caches VERY near to the SECOND viewpoint, for example the Cylch cache GC23DRR.

Additional Hints (No hints available.)



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