What does 'mantle' mean in this context? Is it reference to traditional welsh clothing?
My explanation: mantell y Ddaear, always true as long as you do not put your sofa on the moon. These example sentence do not have a context. That is a certain weakness. Under my sofa you find rather a cloak. :-)
Along with jujoha, I would ask whether this means an article of clothing, such as a cloak, or rather the architectural feature, something like a lintel, over a fireplace.