These flower-shaped pens have only been formally recorded in three other countries – Switzerland, Iceland and Croatia, and Nigel Beidas says South Africa and Jordan have similar structures which merit further study.
Their use in Wales goes back up to 300 years and so the research is documenting an important part of the agricultural heritage.
After walking along the mountains to find them, Nigel takes aerial photos which highlight their beautiful patterns.
He explained how they work to BBC Radio Cymru’s Aled Hughes, as the presenter prepared to walk the North Wales Pilgrim’s Way from Holyhead to Aberdaron in aid of this year’s Children in Need.
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Dim ond mewn tair gwlad arall mae ‘na gorlannau o’r fath wedi eu cofrestru – y Swistir, Gwlad yr Iâ a Croatia.
Mae eu defnydd yng Nghymru yn mynd yn ôl hyd at 300 mlynedd ac felly mae’r gwaith yn cofnodi rhan bwysig o dreftadaeth amaethyddol Cymru.
Gan gerdded ar hyd y mynyddoedd i’w darganfod, mae Nigel yn defnyddio camera i dynnu lluniau o’r awyr i amlygu eu patrymau hardd a’r ffordd maen nhw’n gweithio.
Fe eglurodd y cefndir wrth Aled Hughes, wrth i’r cyflwynydd baratoi i gerdded Taith y Pererinion o Dreffynnon i Aberdaron mewn saith diwrnod fel ei sialens Plant Mewn Angen eleni.