Active Volcanoes in Newfoundland?

As we were recently studying the geology of Newfoundland, someone wondered if we still had active volcanoes.

The short answer is no. All areas that once had them are now so geologically old that once active volcanic regions are long past their active states.

Having said that, a great portion of the central part of the island's crust was built by marine volcanism. Volcanic activity occurred during the Paleozoic about 475 million years ago when the ancient Iapetus Ocean closed and the collision of the African and North American plates led to the creation of the Appalachian Mountains.

This was initially an ocean-ocean collision, very similar to the present type of plate collision that is now forming the islands of Japan. The results were similar as well. Japan is an island arc complex and the same processes were once at work in forming what is now the volcanic portion of central Newfoundland.

Kidney Stones - Are They Rocks, Minerals?

The title says it all...

In some ways, yes. Kidney stones are actually salts and minerals that crystallize in the kidneys.

If small enough (usually less than 3mm), they can pass through the kidney then through the ureters and then on through the bladder and out of the body. If they are too large they will get stuck and hence serious pain will occur.

Like some of the minerals a study in Earth Systems, they do have a similar type of formation. They contain lots of calcium like calcite, and they also crystallize out of a liquid like the precipitates we see in chemical sedimentary rocks. 

Though they contain calcium, they don't usually bond with carbonate or sulfate ions. The most common type of ion they bond with is called the oxalate ion.

Crystallization of kidney stones depends mostly on the amount of acid and the amount of dissolved salts in the urinary tract. Having lots of fluid in the urinary tract would enable salts to stay to dissolved and pass through the body; more salts would crystallize out when a person is dehydrated than when they are hydrated.

So, drinking lots of fluids would guard against kidney stones. They are not good to have.

Some can be even as big as golf balls and are extremely painful.

Potholes - the Road Variety

A recent question came up the other day....

How do potholes form?

This is a good question as it relates directly to geology. We don't cover it specifically in Earth Systems but it does relate to several concepts in the course. It is covered directly in World Geography.

Potholes, the types we see often in our roads in springtime, are a result of physical weathering.

During the winter, water underneath the road freezes and expands giving a frost heaving or frost action effect. The result would be slightly bumpier road or at least areas where the surface would be raised and uneven.

This would leave the pavement more easily broken if it were contacted by the force of a snow plow for example. Over several rounds of snow clearing, the pavement would be more and more broken, starting as several small chips which would lead to wider and wider holes.

Once the pavement is broken and increased water runoff occurs during late winter and early spring, further erosion occur and deepens the hole leading to the types of potholes that cause so much damage to cars.

The pothole problem is quite common in Canadian cities. Here is a brief news story published recently by the CBC.

 CBC Story - Potholes

Of course, there are other types of potholes that form around river beds due to the swirling motion of pebbles as flowing water carries them, but that's a discussion for another post.

Experts at Your Disposal

There aren't a lot of geology related q/a blogs out there, at least not exclusively devoted. After a quick look, I did find one site that contained some very direct questions and answers.

The site is called allexperts, found at:

http://www.allexperts.com/el/Geology/

It offers a host of knowledgeable experts who not only give clear answers, but are also rated.

Extrusive - Intrusive or Plutonic - Volcanic

The title of the post comes from a simpler question....

What is the volcanic equivalent of granite?

The quick answer is rhyolite, but we need to understand why.

The main thing we need to start with is that granite is an igneous rock. Igneous rocks are originally born from the cooling of a melt.

If the melt cools below surface, this is an intrusive environment and the rock is considered plutonic.


If the melt makes it to surface, the environment is extrusive and the rock is volcanic.

The key thing to remember is that you can have the same mineral composition in a melt regardless whether it is plutonic or volcanic. The minerals will be the same but they will cool under different condition and the rocks will have different textures.

So...when a melt containing quartz, feldspar and biotite cools and solidifies in an intrusive environment, the rock is a granite. When it form in a volcanic environment, the rock is a rhyolite - same minerals, different environments.

Superposition

Let's start with one of the simpler concepts in geology...

What is superposition and why is it so important?

Superposition states that in a sequence of layered, horizontal beds (sometimes called strata), the oldest bed (layer) is on the bottom and the beds get younger as you move towards the top of the set.

The law of superposition was proposed by Nicolaus Steno just over 300 years ago.

Superposition assumes that the beds are undisturbed (were not overturned, for example).

It would also work for a series of lava flows that have been laid down, one atop the other in a similar horizontal sequence.

Superposition is an important and fundamental law because it helps determine the relative ages of rock layers.  It helps us determine the geologic history of an area.