The occurrence of chattermark trails varies with weathering on glacial garnet sand grains but not on quartz grains. More garnet grains in contact with humic acids near a soil zone are chattermarked and more chattermark trails occur per grain. Artificial weathering of glacial quartz sand grains in hydrofluoric acid (HF) shows that chattermark trails are originally present though obscure. Visibility of chattermark trails on sand grains is apparently governed by mineralogy and weathering in postdepositional environments. Chattermark trails on glacial garnet grains are consequently unreliable indicators of the degree and multiplicity of ancient glaciations. HF etching reveals obscure chattermark trails on quartz sand grains from a variety of geologic environments. Proposed mechanisms of chattermark-trail formation should not therefore be environmentally restrictive.--Journal abstract.