archaeological & built heritage assessment - The Heritage Council

the aforementioned sites, there are twenty-eight recorded archaeological sites located in Area 1 that are
representative of settlement in the area since Neolithic up to post-medieval times (court tomb / standing
stone / crannóg / churches (4) / earthwork / rectangular enclosure / moated site / castle / ringforts (3) /
cashel / enclosures (3) / holy well / massrock / ironworking (2) /sweat houses (5)). In addition, a number
of chert implements dating from the Mesolithic have been found on the shores of Lough Allen as well as a
series of Bronze Age artefacts. Such early settlement evidence is indicative of the importance of the
waterways corridor as a means of navigation through what would have been a heavily forested and hostile
environment. Industrial development in Area 1 is centred on the iron and coal working within the area of
Arigna, however there is also evidence of isolated iron-workings at Druminalass on the eastern shores of
Lough Allen and at Gubb on the northern shores of Spencer Harbour on the west side of the Lough,
dating to the eighteenth and nineteenth centuries respectively. Also within Area 1 are a series of corn
mills that were indicated on the revised 1910 edition OS maps such as those at Drumristin on the northeastern
shores of Lough Allen, Knockadryan located west of Arigna and Carricknabrack outside
Drumshanbo.
In the 1630s, the Lord Deputy Strafford had proposed linking the major Irish rivers, and the importance of
the Shannon as a line of defence was appreciated by the Confederate forces in the 1640s (Delaney 1987).
After the Restoration one of the ‘Instructions’ issued by the Duke of Ormond was that Ireland’s rivers
should be made navigable. However, it was not until the 1750s before grants were issued by the Irish
parliament in order to undertake proposed navigation schemes. The Grand Canal Company, which had a
vested interest in improving the navigation, took over the Middle Shannon and rebuilt the navigation
works on this part of the river in the early 1800s; the canal company saw little point in opening a canal
from Dublin to the Shannon unless the river itself was navigable.
By the 1820s there was a moderately efficient navigation, but the absence of tow paths made progress
slow on the river sections when boats had to be poled along against adverse winds. The arrival of
steamers in the late 1820s changed all that, but the increasing use of the river focused attention on the
shortcomings of the work already carried out and the locks proved too small to accommodate the size of
steamers which were needed to navigate larger lakes (ibid.). Major works were carried out in the 1840s by
the Shannon Commissioners resulting in the navigation we see today. However this was also a time for
the development of railways and passenger traffic was seriously affected, and in the years to follow
commercial traffic was limited.
Although the early navigation works did not extend above Carrick-on-Shannon, the existence of coal and
iron in the mountains around Lough Allen provided an incentive to attempt opening it up. Some attempts
were made in the 1790s to extend the navigation into the lake by Colonel Tarrant, a military engineer by
making an artificial cut which turned the river Arigna directly into Lough Allen instead of the Shannon (to
avoid silting problems causing rising water levels due to the exit of the lough becoming ‘blocked’) and by
beginning work on a short canal at Battlebridge to by-pass rapids in this area at the west of the river
(ibid.).
The Royal Canal was completed in 1817 with one of the principal reasons for its construction to provide
access by water to the Lough Allen coalfields. As such, it was recommended to make a canal on the east
side of the river all the way to Lough Allen instead of using parts of the river (ibid.). The plan was
approved and the proposal included the deepening of Acres lake, the small lake through which the canal
was to pass. Work began in 1819 and despite some setbacks, was completed and open to traffic in
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