The head of Cwm Orthin is dominated by a large bank of rock waste which was tipped from a tramway leading from Level 9 adit (NPRN 40601) and running between the two ranges of the barracks (NPRN 408867). The 1st edition 25-inch O.S. map of 1889 shows the crest of the tip as 160 metres long, with five much smaller tips of mill waste to the north of the barracks. By 1914 all the tips had more than doubled in volume, as shown by the 3rd edition 25-inch O.S. map of 1919; the crest of the main tip was then 270 metres long. Since 1919 the tips have not grown, other than by the building of two tipping buttresses at the end of the rock waste tip, showing that there was very little production during the last phase of working the mine between 1921 and 1930.
W J Crompton, RCAHMW, 23rd July 2009.