The Clean SWEEP of the Rocky Mountains – #365papers – 2017 – 50

#365papers for February 19, 2017

Chamberlain, Mix, Mulch, Hren, Kent-Corson, Davis, Horton, and Graham, 2012, The Cenozoic climatic and topographic evolution of the western North American cordillera: American Journal of Science, v. 312, p. 213-262.

What’s it about?

This paper uses a compilation of new and previously published oxygen stable isotope data from all over the Rocky Mountain region to understand the timing and uplift pattern of the Rocky Mountains. It seems that the Rocky Mountains first rose to the north, then grew southward. Continue reading

Climate Models and Eocene Isotopes, or How to Make My Head Hurt – #365papers – 2017 – 49

#365papers for February 18, 2017

Feng, Poulsen, Werner, Chamberlain, Mix, and Mulch, 2013, Early Cenozoic evolution of topography, climate, and stable isotopes in precipitation in the North American cordillera: American Journal of Science, v. 313, p. 613-648.

What’s it about?

Isotopes of oxygen and hydrogen in precipitation vary based on multiple factors, including how far from water vapor sources (usually the ocean) the precipitation is taking place, and whether or not there are mountains present, which can deflect and change patterns and amounts of precipitation. Because of this, we can use isotopes of oxygen from rocks and fossils, which reflect ancient precipitation, and understand the pattern and timing of uplifts of mountains.

This paper goes a step further, by using mathematical models to predict what oxygen isotopes of precipitation should have looked like based on a few ideas of how the Rocky Mountains may have come up. Continue reading

Doctoral Day! – Mammals of the Torrejonian-Tiffanian (Paleocene) Transition – #365papers – 2017 – 45

#365papers for February 14, 2017

Higgins, 2003, A Wyoming succession of Paleocene mammal-bearing localities bracketing the boundary between the Torrejonian and Tiffanian North American Land Mammal “Ages”: Rocky Mountain Geology, v. 38.

What’s it about?

This paper discusses the nature of the boundary between two adjacent North American Land Mammal “Ages” (NALMAs). NALMAs are defined by the presence or absence of certain mammal species and are usually quite different in species composition. The 136 localities studied here bracket the Torrejonian-Tiffanian boundary, so we can examine the transition more closely. Continue reading

Snails Tell Tales of Past Climate – #365papers – 2017 – 33

#365papers for February 2, 2017

Abell and Hoelzmann, 2000, Holocene palaeoclimates in northwestern Sudan: stable isotope studies on molluscs: Global and Planetary Change, v. 26, p. 1-12

What’s it about?

By measuring isotopes of carbon and oxygen from fossil snails, the authors were able to determine what the past climate in Sudan was like. Continue reading

#365papers – How to Read Technical Papers… Quickly

I’ve now been teaching science at the college level for over ten years, and actually practicing science for… longer.

One of the challenges that budding young scientists face, as well as those students that take science classes to meet graduation requirements for non-science majors, is that it’s a huge leap from science textbooks, blog posts, and Wikipedia to reading the original scientific literature. Continue reading

You Are What You Eat, Plus a Few Permil – #365papers – 2017 – 20

#365papers for January 20, 2016

Passey, Robinson, Ayliffe, Cerling, Sponheimer, Dearing, Roeder, and Ehleringer, 2005, Carbon isotope fractionation between diet, breath CO2, and bioapatite in different mammals: Journal of Archaeological Science, v. 32, p. 1459-1470.

What’s it about?

This paper discusses how carbon from food becomes incorporated into the tooth enamel of mammals. More specifically, it examines the fractionation in isotopic ratios from food to enamel based upon groups of mammals having different sizes and physiologies.
Continue reading

Hot Times in the Eocene – #365papers – 2017 – 12

#365papers for January 12, 2017

Methner, Mulch, Fiebig, Wacker, Gerdes, Graham, and Chamberlain, 2016, Rapid Middle Eocene temperature change in western North America: Earth and Planetary Science Letters, v. 450, p. 132-139.

What’s it about?

This paper discusses the use of multiple geochemical methods to study an episode of extreme warmth in Earth’s history. The authors were able to determine the magnitude of the warming and used multiple methods to assign ages to the rocks involved. Using other chemical and geological methods, the authors were also able to show how this warming and subsequent cooling changed the overall climate in the interior of North America. Continue reading

Technical Help Needed – IRMS Instrumental Quandry

This is a technical post. I’m writing for other scientists who use the same (or similar) instrument as I do to ask a technical question. I’m having a problem with the mass spectrometer and need the advice of others.

If the mechanics of isotope ratio mass spectrometry aren’t your thing, you might wanna stop reading now. If you’re interested in the types of challenges that arise with these high-falutin’ instruments, you might keep going.

The problem:

I’m getting intermittent power fluctuations through the source. These are little 1-second-long sinusoidal waves of around 10-20mV. These are often overprinted on broader waves or interferences (maybe 100 seconds?) of around 50mV. These are wrecking our analyses. Continue reading

Field Gear – What’s with All the Hammers?

Geologists use hammers. We all possess at least one of the easily recognized ‘rock hammers’ (I have four!). But we don’t all use the traditional rock hammer. And, as I showed in an earlier post, I often take more than one type of hammer to the field.

These five hammers will definitely be going to the field with me.

These five hammers will definitely be going to the field with me.

So, why all the hammers? What difference does it make?

Well, let’s look at the pros and cons of each type of hammer. Continue reading