Mahon Falls aka Eas na Machan EarthCache

The River Mahon flows from the Comeragh Mountains in County Waterford, Ireland. Falling down the Mahon Falls and proceeding past the "Fairy Bush", the river then passes through the village of Mahon Bridge and on past Flahavan's Mill and under the 8-arched rail bridge in Kilmacthomas. In former times, the river powered five different mills, one at Mahon Bridge, three at Kilmacthomas and one at Ballylaneen. The river is joined by the Ách Mór tributary river at Ballylaneen and ends its journey three miles further downstream at Bunmahon on Ireland's south coast. It drains into the region of the Atlantic Ocean known as the Celtic Sea.

Comeragh Mountainsextending from the River Suir valley near Clonmel to the coastal lowland north of Stradbally. Their directional trend is northwest-southeast, and their peaks rise to elevations above 600 m, with the highest point being 792 m. The uplands have been heavily glaciated, resulting in a series of impressive steep-walled corries (ice-scooped basins) including Coumshingaun, a corrie with craggy sides 305 m high around a lake. The mountains are of sandstone and in effect form a single range with the neighbouring Monavullagh Mountains to the south.

Mahon Falls are a series of cascading waterfalls, which flow down the backwall of a glacial corrie, situated along the southern flank of the Comeragh Mountains. The corrie feature was formed during the Quaternary (Ice Age), by glacier ice scouring out a deep, armchair-shaped hollow at the edge of the mountains. The majority of the corrie feature therefore comprises ice-scoured bedrock, which itself is Devonian Old Red Sandstone. The Mahon River, which rises from a series of seeps in blanket peat in the high plateau of the Comeraghs, flows down the backwall of the corrie creating a series waterfalls over each of the thicker conglomerate or sandstone beds.

This corrie has a very steep backwall up to 300m in height and the Mahon River has gullied the backwall, creating a shallow gorge along part of the stretch of waterfalls. The base of the corrie hosts no lakes, but the Mahon River flows through the centre of this along a meandering path, which is initially surrounded by hummocks and boulder moraines, but further down-valley becomes a flatter, less stony, till plain. The moraines comprise welldrained material, which is strewn with erratic boulders, many of which are several metres across. The eastern side of the corrie has some well-expressed scree slopes. As corries usually only take flows of water from a relatively restricted up-gradient catchment, the waterfalls are unusual in that a sizeable stream happens to flow across the backwall. Owing to this, the falls can become a torrent in wet weather as the river swells.

The Old Red Sandstone describes a suite of sedimentary rocks deposited in a variety of environments during the Devonian but extending back into the late Silurian and on into the earliest part of the Carboniferous. The body of rock, or facies, is dominated by alluvial sediments and conglomerates at its base, and progresses to a combination of dunes, lakes and river sediments. The familiar red colour of these rocks arises from the presence of iron oxide but not all the Old Red Sandstone is red or sandstone — the sequence also includes conglomerates, mudstones, siltstones and thin limestones and colours can range from grey and green through red to purple. These deposits are closely associated with the erosion of the Caledonian Mountain chain which was thrown up by the collision of the former continents of Avalonia, Baltica and Laurentia to form the Old Red Sandstone Continent- an event known as the Caledonian Orogeny.

Waterfall Classifications:

• Ledge Waterfall: Water descends vertically over a vertical cliff, maintaining partial contact with the bedrock.
• • Block/Sheet: Water descends from a relatively wide stream or river.
  • Classical: Ledge waterfalls where fall height is nearly equal to stream width, forming a vertical square shape.
  • Curtain: Ledge waterfalls which descend over a height larger than the width of falling water stream.
• Plunge: Fast moving water descends vertically, losing complete contact with the bedrock surface. The contact is typically lost due to horizontal thrust of the water before it falls. It always starts from a narrow stream.
• • Punchbowl: Water descends in a constricted form and then spreads out in a wider pool.
• Horsetail: Descending water maintains good contact with bedrock most of the time.
• • Slide: Water glides down maintaining continuous contact.
  • Ribbon: Water descends over a long narrow strip.
  • Chute: A large quantity of water forced through a narrow, vertical passage.
  • Fan: Water spreads horizontally as it descends while remaining in contact with bedrock.
• Cascade: Water descends a series of rock steps.
• Tiered/Multi-step/Staircase: A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool.
• Cataract: A large, powerful waterfall.
• Segmented: Distinctly separate flows of water form as it descends.
• Catadupa: A cataract or waterfall, originally those of the Nile. The term catadupae refers to people inhabiting near such cataracts; there are suppositions that these people are deaf due to the constant din.
• Tide Fall: A waterfall that directly empties into the sea or ocean.
• Frozen: Any waterfall which has some element of ice.

Questions to Answer:

1. Estimate the height of the waterfall.
2. What type of waterfall classification is this?
3. What evidence of glaciation do you see in the corrie?
4. The rock that the Mahon Falls flows over is a harder substance than the sandstone. Describe its texture, color, and hardness. You can use the Mohs scale for the hardness.
5. Please upload a picture of your experience. (optional)