Editorials

Looking down on the Earth from space, the Alps appear to be a small, and possibly unimportant, adornment to the tremendous girdle of “Alpide” orogens that stretch the full width of the southern margin of the Eurasian continent. But seen up close, and with historical perspective, the Alps punch far above their weight. From the deepest prehistory of our hominid ancestors to the modern age, the Alps have been a formidable barrier to trade, communication, migration, and conquest across the small, but storied, “peninsula” of Europe—a fact brought home for me when I recently toured a museum in Bolzano (Italy) dedicated to the life and remains of “Ötzi”, a man who met his end five thousand years ago in the high peaks and ice fields of the Ötztal Alps.

As someone who firmly sits on the “Lab Rats–Computer Geeks” binary join of the geoscientist ternary diagram (Fig. 1), putting together this “Hydrothermal Fluids” issue of Elements has brought back some vivid memories of my yearly foray into field teaching. Faced with the task of explaining some complex, but fundamentally important, geological process encoded into the face of an outcrop, I would get the inevitable student question: “But why does that happen?” Invariably, my mumbled response would be, “Because of fluids….”. As pointed out – more expertly – by this issue’s guest editors Matthew Steele-MacInnis and Craig Manning, very little happens on Earth without with involvement of fluids, a fact that becomes immediately evident in the field, well away from the clean, dry and highly controlled laboratory environment that I am more comfortable inhabiting. Having finalized this issue, I am looking forward to giving much more detailed answers in the future!

Time is a big deal for us geologists. Rates of Earth processes range from the mind-numbingly slow (mantle convection) to the catastrophically fast (volcanic eruptions) with everything in between. Geologists move effortlessly from units of seconds to giga years in a way that often confounds scientists in other disciplines; no geologist is unaware of humanitys’ fleetingly brief tenure of the planet in the grand scheme of things.