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February 5, 2023
Geology Word of the Week: N is for Notebook
def. Notebook: A small book for recording notes, such as geological data. Since geologists often have to record notes in rainy (and sometimes snowy!) conditions, they prefer to use notebooks made with special paper that is water repellent and can be written on with a pencil or special pen even when there is precipitation. When I was a geology student, I quickly learned that conducting geological fieldwork with …
January 29, 2023
Geology Word of the Week: M is for Mica
def. Mica: A term used to describe a group of minerals that form in flat layers (or sheets) and have a vitreous or pearly luster (they are shiny!). Micas are phyllosilicate minerals, also known as “sheet silicate” minerals. Micas are common rock-forming minerals, although some varieties are harder to find than others. Micas come in many different colors. Common mica minerals include muscovite (clear), biotite (black), and phlogopite (dark brown). …
January 15, 2023
Geology Word of the Week: L is for Luster
def. Luster (or Lustre if you use British spelling): The way in which the surface of a mineral or rock interacts with light. Words used by geologists to describe luster include metallic, sub-metallic, dull (or earthy), vitreous, waxy, silky, greasy, pearly, and adamantine. Luster is a physical property that is used by geologists to help identify minerals and rocks. Other physical properties that geologists use for identification are …
January 6, 2023
Geology Word of the Week: K is for Karst
Several years ago, I used to write a “Geology Word of the Week” post in which I selected a word used by geologists, wrote a definition of the word, and wrote up a post with some information and pictures related to the word. I went through the alphabet in order twice, writing about words starting with letters from A to Z, and then I started a third run through the …
January 7, 2015
Geology Word of the Week: I is for Ice
def. Ice: Water (H2O) in a solid state. When naturally occurring, ice is considered a mineral. There are many forms of ice: lake ice, river ice, sea ice, snow, glaciers, ice caps, ice sheets, and frozen ground (such as permafrost). If you ask a geologist what he or she considers to be Earth’s most important mineral, you will probably hear many different answers, depending on the person. Some might …
January 1, 2015
Geology Word of the Week: H is for Hand Lens
I’ve decided to bring back the long-lost “Geology Word of the Week” posts in 2015. For those of you who don’t know, for a few years I regularly posted about a geological word every week. These posts included a brief definition (written by me) of the word and then some additional information and pictures. However, starting in 2012 I stopped posting these words regularly. I was quite busy in 2012 because …
December 16, 2012
Geology Word of the Week: G is for Glacial Erratic
def. Glacial Erratic: A rock which has been transported and deposited by a glacier and which has a different lithology than the rock upon which it has been deposited. Often, erratic rocks have an angular shape because they were broken off of bedrock by glaciers and have not yet had time to be weathered and rounded by water, wind, and other erosional forces. Glacial erratics can range in size from very …
December 9, 2012
Geology Word of the Week: F is for Float
def. Float: Loose pieces of rock that are not connected to an outcrop. If you’re in the field with a geologist, you’re very likely to hear the word “outcrop” and the phrase “in situ“. When describing, identifying, mapping, and understanding rocks, geologists like to see rocks in context. If rocks were alive, you might say that geologists like to observe rocks in their natural habitats. You might say that geologists …
December 2, 2012
Geology Word of the Week: E is for Eurypterid
def. Eurypterid: 1. A group of extinct arthropods that were fearsome marine predators of the Paleozoic. There were over 200 different species of eurypterid, and they ranged from very small (less than 20 cm) to very large (greater than 8 feet). Because of their long tail, eurypterids are sometimes called “sea scorpions.” Indeed, they are closely related to today’s scorpions and other arachnids. One species of eurypterid, Eurypterus remipes, is the …
November 23, 2012
Geology Word of the Week: D is for Drumlin
def. Drumlin: An elongated hill or ridge with a shape resembling an upside-down spoon or a half-buried egg that was formed out of glacial till– and sometimes other material such as gravel and even bedrock– that was shaped by the movement of a glacier. A drumlin carved in bedrock is usually called a “rock drumlin.” Drumlins have a steeper end and a less-steep, more tapered end. The shape of a …
