Tag Archives: Rocks

Geoscientist’s Toolkit: Sample Bags

Sample bag and purple volcanic ash.  Yellow tag is 5 cm by 7 cm.  Image credit: Bill Mitchell
Sample bag and purple volcanic ash. Yellow tag is 5 cm by 7 cm. Image credit: Bill Mitchell

Often when in the field, it is useful to bring back samples of rock. To keep samples labeled and contained, each sample is put into its own sample bag, which is then labeled and securely tied shut.

I have used both cotton and synthetic sample bags (the one shown above is synthetic), and generally prefer the cotton. The bags are a bit sturdier, and with some of the rocks I sample being fairly pointed, they hold up more nicely in shipping. Sturdy cotton sample bags are also a bit heavier, so on expeditions where every ounce matters, the synthetic may be the bag of choice. My samples are also generally dry, but in wet environments the cotton sample bags may not be appropriate as they may degrade during shipping.

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Geoscientist’s Toolkit: Rock Hammer

Hammer for scale rests on a silicic dike in the Benton Range, near Bishop, CA.  Image credit: Bill Mitchell.
Hammer for scale rests on a silicic dike in the Benton Range, near Bishop, CA. Image credit: Bill Mitchell.

In the field, a rock hammer can be a very versatile and useful tool. One of its primary purposes is to give a sense of scale to photos which otherwise would lack one (see above). A related use is pointing to a specific feature in an outcrop photo, such as an interesting layer of sediment or a fossil.

Finally, and perhaps the use most people would think of, is to make big rocks into smaller rocks (while wearing appropriate eyewear and other protective clothing). Often rocks at the surface have been subject to weathering from sun, wind, and rain. To get to fresh, unweathered rocks, it is necessary to dig back into the rock face. Upon reaching fresh rock, the rock hammer can be used to break off smaller bits that can be analyzed back in the lab.

Geoscientist’s Toolkit: Camera

Columns of the Giants.  Image credit: Bill Mitchell
This is not a camera. It is a picture of Columns of the Giants, taken with a camera under less-than-ideal lighting conditions. Image credit: Bill Mitchell

A good camera is handy to have in the field. You can capture in a picture more details than you can sketch in a reasonable time. Additionally, if you sketch like I do, the picture will be far more accurate in its recording of what you are seeing. For instance, the above photo shows Columns of the Giants, from well up into the Sierra Nevada range in California. From this picture, you could estimate cliff height, the height of the columns (at the base of the cliff), the typical size of the columns, and so forth.

One or two lenses are generally sufficient: a wide-angle lens to get big features (choose this if there can be only one), and a macro lens for close-ups.

When taking pictures, it is important to include a scale of some sort. It can be a finger, shoe, pen, hammer, person, truck, whatever. Just make sure there is some context for the size of the image. I was reassured when, in my quest for a scale-less picture for last week’s post, I had difficulty finding one. For many places, you might get by if you forget. However, on Heard Island, the barren and alien landscape will not be so forgiving.