Eruptions Word of the Day
eklemetti | August 1, 2010Continuing my series where I try to define words of volcanic interest, the new Eruptions Word of the Day is a favorite of mine, mostly because my undergraduate thesis on Vinalhaven Island in Maine ended up dealing with a lot of these types of deposits ... so, without further ado, the word is peperite!
Now, what exactly is a "peperite"?
Well, a picture is worth 1,000 words, right (so that will save me some time):
Peperite in the Vinalhaven Diabase, Vinalhaven Island, Maine. Image by Erik Klemetti. Click on the image to see a larger version.
Let's make some observations:
The rock is full of…
eklemetti | July 12, 2010The latest Eruptions Word of the Day is "Tuya".
So, what is a tuya?
This is a tuya:
A tuya! Click on the image to see a larger version. Image by Erik Klemetti.
Alright, well, that doesn't entirely help, does it?
Lets look at the feature the arrow indicates. Some observations:
(1) It is low and broad.
(2) It has a relatively flat top.
(3) It is steep-sided.
(4) If you look real close, you can see crudely columnar jointing in the some of the outcrops near the top.
(5) If you had a piece of it in your hand, you'd know it was a volcano rock (andesite, very rarely you can find bits that are quite…
eklemetti | July 4, 2010So, I've had requests on the blog to help to do some defining of volcanologic terms on the blog, so I thought I'd try a new column called Eruptions Word of the Day. I'm not sure how often it will run, but let's give it a try.
Eruptions Word of the Day for July 5, 2010: Dacite
Dacite is a magma type defined by silica (SiO2) content between 63-68 (or 69) weight percent. That is the textbook definition, but some other typical characteristics of dacite lavas (or magmas) is the presence of certain minerals: plagioclase feldspar and hydrous minerals (containing water in their mineral structure)…