Template:POTD/2011-06-23
{{POTD {{{1|{{{style|default}}}}}}
|image=Desiccation-cracks hg.jpg
|title=Mudcrack
|texttitle=Mud cracks
|caption=Mudcracks in sludge, the remains of a sewage treatment plant in Kos, Greece. Mudcracks naturally form when wet, muddy sediment desiccates, causing contraction through a decrease in tensile strength. Individual cracks join up, forming a polygonal, interconnected network. These cracks may later be filled with new sediment, forming casts on the base of the overlying bed.
|credit=Photo: Hannes Grobe