Primary Cluster 1 covers approximately 18,833km2 of land area, substantially larger than Primary Cluster 2 which covers 1,902km2.
Mae Prif Glwstwr 1 yn rhychwantu tua 18,833km2 o arwynebedd tir, sy’n sylweddol fwy na Phrif Glwstwr 2, sy’n rhychwantu 1,902km2.