jarosite KFe3(OH)6(SO4)2. A pale yellow potassium iron sulfate mineral.
joint [geology] A surface of actual or potential fracture or parting in a rock, without displacement; the surface is usually planar and often occurs with parallel joints to form part of a joint set; also called joint planes (Hawley and Parsons, 1980).
joint planes Planar voids that traverse the soil material in some fairly regular pattern, such as parallel or subparallel sets.
jokulhlaup (Pronounced: yo-kool-loup, the last syllable as in “out”.) An Icelandic term for a glacial outburst flood, especially when an ice dam impounding a glacial lake breaks. Such breaks drained glacial Lake Missoula and created the Channeled Scablands in the Pacific Northwest (Schoeneberger and Wysocki, personal communication, 2013; Jackson, 1997). Compare glacier outburst flood, scabland, giant ripple.