We continue our Hypogenic Caves Series this month with Harvey DuChene giving two consecutive talks, first on Carlsbad Cavern and the second on Lechuguilla Cave. He will talk about the evidence that these caves provide for their hypogenic, sulfidic origins as part of our continuing process of informing ourselves on ways to critically look at Great Basin caves. The presentations are expected to last less than an hour and will be followed by a typical grotto meeting, including trip reports and trip announcements.