Yet another form of plastic pollution - "plastiglomerate" - rock-like fragments of plastic, sand grains, debris and organic materials fused together by human-induced fires. 

In certain areas of the Great Lakes surface densities of plastics are as high as those reported for areas of litter accumulation within ocean gyres.  Sources include microplastic beads, consumer products, industrial pellets, and waste from beach-goers, shipping, and fishing activities.

Prof. Patricia Corcoran, Dept. of Earth Sciences, University of Western Ontario, explains what plastiglomerate is and where it came from.

Also, Greta Thunberg's speech at the World Economic Forum - Davos.