What do you think of his definition of a volcano? Does it fit what you observe on Earth? With this definition, some phenomenon we do not think of as volcanic are dragged into the volcanic world. Thermal springs, for example, are a consequence of internal thermal processes, but we do not think of them as actively volcanic. The problem here is that we need to extend our earth-bound definitions to encompass a plethora of extraterrestrial phenomena on frozen worlds where liquid water (or methane or ammonia) is as much lava to the substance of that planet/moon as our incandescent silicate lava is to the mantle of the Earth.
A note on units
You may or may not be familiar with the units used in this text. A simple Google search will get you to a satisfying definition in most cases, but you can always ask me if there is something that is unclear or confusing.
- Joules is a measure of energy like the more familiar (all too familiar!) calories
- 1 x 106 is the same as 1,000,000, or 1 followed by 6 zeros, that makes it a million
- A Watt (or smaller milliwatts= thousands of a Watt) is a measure of power, or the “flow” of energy.
- Myr is millions of years
- PPM is a measure of concentration in parts per million
All the chemical elements have symbols
- U is uranium
- Th is Thorium
- K is Potassium
Isotopes
Each element has an atomic number based in the total number of both protons and neutrons in the nucleus. Each element can also exist in a number of forms based on a naturally variable number of neutrons in the atomic nucleus. These “forms” are called isotopes. U235 U 236 (read “uranium 235 and uranium 236”) are both naturally occurring isotopes of uranium, each with the same number of protons in the nucleus, but different numbers of neutrons. Many of these isotopes are unstable over time and break apart (decay) to produce different elements with the loss of energy. Thus, radioactive potassium (K) 40 decays over time to produce Argon gas and Uranium decays to produce different isotopes of Lead.
Ions are atoms either missing some of their electrons or carrying one or two too many! They have an electrical charge that can be positive (cation) or negative (anion).
Kinetic energy is the energy of movement. Hit your hand on the desk (ouch!) Hit is faster (bigger “ouch”). Welcome to the world of kinetic energy. This is a function of the mass of an object and its velocity. The faster the same mass is moving, the more kinetic energy it has, and as with all energy, this can be converted itno other forms of enrgy, most commonly thermal energy, on collision with another object.
Tidal energy is due to the effect of gravity of one object on another. In this case, gravitational energy is converted into internal deformation of a planet/moon and this leads to the generation of heat. Take a large paper clip. Twist it until it breaks. Quckly feel the broken ends. They will be hot due to the release of energy through deformation (in this case by your hands instead of gravity).
Remember the Earth is like an onion (or Ogers if you are Shrek fan). There are layers. The outer, very thin, layer is the crust. The thickest layer (100km -2,900Km deep) beneath is the rocky mantle (still solid for most part). Some 6,000Km deep lies the metallic core. There are two parts to the core, a liquid, molten outer core and a solid inner core.
Kimberlites…where we get diamonds from!
Do not try to remember the names of all the minerals or rock textures mentioned in this book. The list of minerals on page 12 is quite important, however, so have a go at remembering (or least recognizing) these ones.
On page 13 he writes about Sodium and Potassium as “Na2O and K2O”. These are not the elements (Na and K), but oxides of the elements; we geologists just get sloppy sometimes and that infuriated newcomers like yourselves.