This clay country of the riverine plains of Queensland and New South Wales periodically is wet by overland flows of water and becomes wet to quite some depth. With each wetting, the clays expand and so the surface becomes undulating or pocked with swelling and hollows. The hollows can be from the size of a watermelon to 50-100M in length. On drying the clays shrink and crack open. As the cracks gradually fill with dust and dry debris and then with soft mud washed in as water arrives, the soil in the hollow expands once again raising the surface around it, accentuating the hollow. This patterning of the ground is similar to that which happens in tundra landscapes as the wet surface layers expand on freezing. Such cryoturbation produces patterned ground of shattered stone, the particular pattern determined by the angle of the slope.
In Australia, the indigenous word used for the melon-hole country is gilgai.
From the air the patterned ground of the gilgai is most obvious after a wet period when water and green vegetation accentuate the visual pattern.
Thank you for that fascinating description of how the gilgai is created, Ian. What a lovely effect it gives, too.
I never cease to be amazed and enthralled by the natural phenomena around us. Sometimes I wish I had 4 eyes (2 at the back of my head as well) to just not miss out on anything!! ((o;
Warmest wishes, Hazel (chameleon-envier)
Your responses are very encouraging to this geography teacher who both enjoys the natural landscapes and loves to inquire and to teach. I presume the same phenomenon occur in southern Africa as well. Out Etosha and Okavango way, surely. (I must explore GE.) I wonder what the local names are for melon-holes.
Best wishes, dear friend,
Beautiful shot! Like 1
Invite the group Aerial photos.
Thanks László. I have added it to the group gallery.
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Photo taken in Dirranbandi QLD 4486, Australia
Misplaced? Suggest new location