Lichen sheds new light on portal tomb cairns

Title image: Pentre Ifan Dolmen, Pembrokeshire

Could lichen growth on portal tombs give us a clue to the original height of the cairns which once covered these tombs?

An interesting article in the Autumn 2019 issue of ‘Archaeology Ireland’ leads us to think differently about the cairns that covered portal tombs. Evidence from the lichen suggests that the cairn covering only went so far up the tomb and that more of the impressive dolmen-like structure would have been visible than if it was completely covered.

Portal tombs are the most striking of the Neolithic tombs and are characterized by their enormous capstones, balanced precariously on a few upright stones.  Typically, the chamber has two portal stones which form the entrance and these can be impressively high, as in Legananny tomb below. They have a single large capstone which slopes down onto a backstone at the rear. More stones would have formed the walls of the chamber but these didn’t support the capstone.

Legananny Portal Tomb, County Down

There are about 180 known portal tombs in Ireland with the largest number of them being in the northern part of the country. They are also found in Wales , mainly in the extreme south west, and in Cornwall. In Wales and Cornwall they are usually called cromlechs or dolmens – but not all cromlechs or dolmens are of the portal tombs design!

Many portal tombs have evidence of a long cairn which would have stretched out behind the chamber, making a long trapezoidal-shaped mound. It has often been thought that this cairn also covered the chamber and only the entrance would have been visible. However, it now seems that this may not have been the case.

Ballykeel Portal Tomb, County Armagh

Eoin Halpin, in his article “Growing evidence for portal tomb cairns?” has examined lichen growth on many portal tombs in Ireland and found that on the external upright stones there is often a marked difference in lichen growth between the upper and lower parts of the stones.

A ‘tideline’ is usually visible, where the lichen above it is much more profuse and of a greater variety than the lichen below the line. Lichen needs sunlight to grow and the density of lichen above a certain height could indicate that that part of the stone had been exposed to daylight for much longer, while the stone below had been hidden from daylight by the cairn material.

 The conclusion is that cairn material was only built up to a certain height, so that people would probably have been able to see the capstone and part of the structure.

The lichen evidence supports the views of other archaeologists who have come to the same conclusion that part of the tomb structure was left open to view and that the cairns covering portal tombs were not as high as originally thought.
 It makes sense that these fine structures, which were far from easy to build, were built to be seen, and that the tombs were as impressive looking in their day as the monuments we see left in the landscape today.

Goward Portal Tomb, County Down

Reference: Growing Evidence for Portal Tomb Cairns, Eoin Halpin ponders lichen growth as an indicator of cairn height. Archaeology Ireland, Issue No.129, Autumn 2019

Links to other posts about Portal Tombs:
Pentre Ifan
Ballykeel Portal Tomb
Goward Portal Tomb
Dolmens of County Down
Proleek Portal Tomb

Proleek, Co. Louth

Dolmens of County Down

Some dolmens of Co. Down, from the much photographed Legananny (below) to some in  rather surprising places!

Legananny Dolmen

Built in an elevated position on the slopes of Slieve Croob  and looking towards the Mountains of Mourne, Legananny is one of Northern Irelands best known dolmens.

This extremely tall portal tomb is made of granite and has a large capstone slab finely balanced on the points of three tapering pillars.
Many dolmens are associated with figures from ancient legends and Legananny, is a translation from the Gaelic, Liagan Aine, meaning pillar stone of Aine.

Around the winter solstice the morning sun shines through the two portal stones, illuminating the underside of the capstone.


Continue reading “Dolmens of County Down”

Carrowmore Neolithic Cemetery, Co. Sligo

One of the small cairns, with Benbulben to the north

Carrowmore is one of the four great megalithic cemeteries in Ireland and is situated in the centre of the Cuil Iorra peninsula in Co. Sligo. It covers an area of 3.8 sq km (1.5 sq miles) and with its large central cairn and 30 surviving small burial cairns, it is the largest, and probably the oldest, of the Neolithic cemeteries.

Carrowmore (a)
The massive cairn of Listoghil viewed from one of the small tombs

Listoghil is the large tomb at the centre and highest point of the Carrowmore tomb complex. It was reconstructed in 2004 and shows what it would have originally looked like (at least, from the outside) with it’s large cairn of stones surrounded by kerb stones at the base.

There are about 30 smaller and simpler cairns surrounding Listoghil and these are typically a dolmen construction surrounded by a small stone circle, or in some cases, two circles. There were originally many more, perhaps about 80, and they would probably have been built by small groups of people at an earlier date than the building of the big, impressive passage tombs. It is quite likely that these tombs were never covered by cairns.

Looking over the Carrowmore tomb complex is the striking limestone hill, Knocknarea, with Miosgan Meadhbha (Queen Maeve’s Cairn) clearly visible on the summit. The legend is that this was the burial chamber of Queen Maeve of Connacht . The massive cairn has never been excavated but it is believed to be a Neolithic passage tomb. Also on the summit, are the remains of smaller tombs, probably small passage graves.

Knocknarea from Carrowmore

The size of the cairn on the summit of Knocknarea can’t be appreciated from this photo, but it is a massive 55m wide and 10m high, making it the largest cairn in Ireland after those at Brú na Bóinne.

Ballykeel Portal Tomb

Ballykeel Dolmen (2)

Also known as the Hag’s Chair, it is situated on a terrace of flat land ringed by the low rugged hills of the Ring of Gullion in Co. Armagh.
Like many portal tombs, it was built in the Neolithic period but used again in the Bronze Age and also has the common feature of the entrance facing a stream.

Excavation in the 1960’s revealed that it had an octagonal burial chamber under the capstone. Many sherds of Neolithic pottery and some flint tools were found. The portal tomb would have been covered by a cairn of stones which extended back from the tomb by 25m, giving it the appearance of a long cairn.  The remains of this can still be seen. The Bronze Age stone burial cist was inserted into the cairn material.

Ballykeel Dolmen (6)
The information board with a drawing of how the cairn would have looked

Ballykeel Dolmen (7)
Standing on what remains of the cairn material, looking towards the dolmen at the south end

Ballykeel Dolmen
Looking from the tomb towards the end of the cairn. The hills forming part of the Ring of Gullion volcanic ring dyke are in the background.

Goward Portal Tomb

This portal tomb has the wow factor!  For the sheer enormity of the capstone and the location. It is situated at the top of a little glade-like field and below it are the moss covered remains of an old cottage. These photos were taken on a damp grey day but the banks of primroses added a splash of colour and the atmosphere was enhanced further by the inquisitive baby lambs in the adjoining field and by a stoat which went back and forth across the glade, carrying it’s young (5 in total) from one nest to another.

Goward Portal Tomb (3)

The capstone, which is estimated to weigh about 50 tons, has slipped to the side, revealing the chamber underneath. When it was excavated around 1834 cremated bones and a flint arrowhead were found.
A small standing stone by the front of the tomb may be all that remains of a forecourt.

Goward Portal Tomb (1)

Goward Portal Tomb (2)

The dolmen is also known as Pat Kearney’s Big Stone and the information board has a 19th century photograph on it of a thatched cottage and a man sitting beside the dolmen – possibly Pat Kearney himself?

Goward Portal Tomb (4)

Located off the B8 between Hilltown and Castlewellan in Co. Down. It isn’t signposted from the B8 but once you get onto the right country lane it is well signposted and has a small parking area and information board beside it.

A nearby Bronte connection

A shebeen on the Bronte Homeland  Trail
A shebeen (illicit drinking house) at Knockiveagh picnic site on the Bronte Trail

As a bit of a diversion from the prehistoric, the Bronte Homeland Trail is worth a mention here. It is about 5 miles away, north of Rathfriland and starts at the Interpretation Centre at Drumballyroney Schoolhouse and Church.
Patrick Bronte, father of the famous sisters, was born into a poor farming family in this area. He was the eldest of 10 children and taught at Drumballyroney School for 4 years before going to Cambridge to read theology.  Adjacent to the school is the Anglican church where Patrick returned to preach his first sermon after graduating.
Charlotte’s husband, Arthur Bell Nicholls, had a  similar background to Patrick, coming from a farming family of 10 children in County Antrim.

There aren’t any prehistoric monuments on the trail but it is worth driving it for the Bronte connections and the views across the countryside to the Mournes.

Proleek Portal Tomb & Wedge Tomb, Co. Louth

Proleek Dolmen is an excellent example of a portal tomb and dates from at least 3000BC. It has 2m high portal stones at the front, a small stone at the back, and perched on top is a huge capstone weighing 36-40 tons.

The tomb is also called The Giants Load and legend has it that you will be granted a wish if you throw a stone and it stays on the top. Another legend is that if the stone stays on top you will be married within a year.

Proleek Dolmen with its covering of pebbles that stayed on top!

100 yards away is a wedge tomb, so called because of it’s shape – wide at the front and tapering in towards the rear. This one still has a large capstone in place across the top of the narrow end of the tomb.
Wedge tombs are the most numerous type of megalithic tomb in Ireland but are not so common down the eastern side of the country.

The tombs can be accessed via a signposted path from the car park at Ballymascanlon Hotel ( I can recommend the hotel – it is excellent!).  It’s a very pleasant walk past the gardens and old stables at the back of the hotel, down a lane and then quite a long walk on a path across the golf course (there’s screening in places to prevent you being hit by golf balls).