Stickers are again available. Suitable for anyone interested or disinterested in subsurface production, although still slightly misleading for C-14. Send a stamped, self-addressed envelope to: Greg Balco, BGC, 2455 Ridge Road, Berkeley CA 94709 USA. I will put some stickers in it and drop it back in the mail ..read more

This is yet another post about using the ICE-D:ANTARCTICA database of exposure-age data from the Antarctic continent to learn something interesting about past changes in the Antarctic ice sheets. And it’s also another post focused on trying to digest the whole data set into a single figure. However, instead of focusing on what ice sheet changes are recorded in the exposure-age data set, it focuses on ice sheet changes that aren’t recorded. Yet. Specifically, hypothesize that in the process of shrinking from its Last Glacial Maximum size to its much smaller present size, the ..read more

Cosmogenic-nuclide geochemistry is not generally noted for being anything like real life. It can’t even be explained to most folks without a 20-minute briefing on nuclear physics, and it is rare to find any normal person off the street who is even willing to get through the entire 20 minutes. The business model for the field involves taking bright undergraduates with many skills and great potential for success…and using the lure of exotic fieldwork in places like Antarctica and Greenland to systematically divert them into successively more arcane graduate programs, eventually leading to an unl ..read more

This post is not so much about how one generates cosmogenic-nuclide exposure-age data, but what one does with it. Especially when you have a lot of it. The example focuses on exposure-age data from Antarctica that record the LGM-to-present shrinkage of the Antarctic ice sheets. First, the background. Right from the beginning of exposure-dating, one of its most useful applications has been figuring out what happened to the Antarctic ice sheets. Even though only a tiny amount of Antarctica is actually ice-free at the moment, the areas that are ice-free are thoroughly stocked with glacial deposit ..read more

For the last several years, folks interested in computing exposure ages from beryllium-10 or aluminum-26 measurements have enjoyed a proliferation of online exposure age calculators enabling them to do this. This seems like a good thing, because it’s useful to be able to make sure that whatever conclusion you are trying to come to doesn’t depend on the specific calculation method you chose — it should be true for any reasonably legit method and choice of parameters — and, in addition, competition keeps prices down. In fact, this works so well that all the online exposure age calculators are fr ..read more

This is another post about the very slow upgrade of the online exposure age and erosion rate calculators to the latest version 3. As alluded to in the previous post, erosion rate calculations somehow always seem like a lower priority, and that part of the upgrade was a bit delayed. However, the version 3 erosion rate calculator is now more or less complete (although a couple of interesting bugs having to do with very high erosion rates survived until a couple of weeks ago and have just now been fixed), and seems to be mostly in use. However, one problem with the version 3 erosion rate calculat ..read more

No, not switch governments — switch exposure-age calculators. Sorry. This post is about the really excessively long transition from the not-so-recent to the most-recent version of the online exposure age and erosion rate calculators. It is true that this subject is less important than the news of the day, which is that the entire top of the US military command structure, including the Joint Chiefs of Staff, is now in preventative quarantine. Leaving that aside for the moment, though, the background to this post, detailed here, is that various iterations of the so-called “version 2” of the onli ..read more

Neon-21 is now ‘trending’ on this website, because this is the second post about it this year. The purpose of this one is to try to unscramble the tedious and obscure subject of production rate calibration for cosmogenic neon-21 in quartz. Eventually, at the end, it describes an update to the part of the online exposure age calculator dealing with Ne-21, which doesn’t fix everything, but is a legitimate conceptual improvement and results in only small differences between Ne-21 exposure ages calculated before the update (i.e., yesterday) and after (today). Even though Ne-21 production in quartz ..read more

Based on recent emails, a common complaint about version 3 of the online exposure age calculator is that when you calculate an exposure age, the results page does not include the nuclide production rate at the sample location. This was a feature of the version 2 exposure age calculator that apparently was much more widely used than I thought. Some users then proceed to further confusion about whether or not the production rate calibration input page is intended to be used for this purpose. Of course this is not the case — production rate calibration is something quite different. The main reaso ..read more