Fig. 3. High resolution stereo scanning electron micrographs of particle surfaces from the untreated (A) and H₂O₂-treated (B) fine clay fraction of the Webster soil. The prominent ropy structures are believed to be wrinkles in the surficial smectite layers. Subtle blotchy features between the ropy structures seen in A but not seen in B are believed to be diffuse filamentous coatings of humic materials. The volcano was probably caused by a gas bubble that burst through the top smectite layer when the sample was evacuated.