👷AGY201. EARTH HISTORY

-

Earth History
🟢 *STRATIGRAPHY*
This is a branch of geology that deals with the study of rock layers and layering. Also used in the study of sedimentary and layered volcanic rocks.
   Its scientific discipline is concerned with the description of rock successions and their interpretation terms of a general time scale.

*PRINCIPLES OF STRATIGRAPHY*
All geologists use these principles in deciphering the spatial and temporal relationship of rock layers. The laws were developed in the 17th - 19th centuries based upon the work of *Nicolaus Steno (1669), James Hutton and William Smith*

(1) *PRINCIPLE OF UNIFORMITARIANISM*
This states that "the present is the key to the past".
It allows us to interpret the events of the past in rocks; it allows us to write the history of Earth.
   In addition to allowing the interpretation of the past, it allowed the prediction of the future.

(2). *PRINCIPLE OF SUPERPOSITION*
This states that " in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom; each layer being younger than the one beneath it and older than the one above it.
Nicolaus Steno in 1669 also formulated this law.

(3). *PRINCIPLE OF FLORAL AND FAUNA SUCCESSION*
Flora is plant life, while fauna refers to animals.
*Fossils* are physical evidence of preexisting organisms, either plant or animal. Obvious fossils are the preserved skeletal remains of animals.
  Other fossils which are also evidence of past organisms include tracks and trails, burrows, droppings and root casts.
  The principle states that *"faunas and floras succeed one another in a definite recognizable order"*
Faunal succession is the fundamental tool of stratigraphy and comprises the basis for the geologic time scale.

  


🟣 *MINERALS*
Geology deals with the physical and historical aspects of the Earth.

*Physical geology* is the study of the composition, behavior and processes that affect Earth's lithosphere

*MINERALS* are basic building blocks of nearly all Earth materials for most geological purposes. It is also a naturally occurring, solid, inorganic combination (compound) of one or more elements whose atoms are arranged in an orderly fashion (crystallinity) and has an established chemical composition that can vary slightly within specific limits.
Crystal structure is redundant.

Minerals like glass and opal have no particular geometric arrangement of their atoms (they are not true minerals because they lack crystallinity).
Mineraloid is used for these materials and some mineraloids are simply called rocks. (natural glass, obsidian is a kind if volcanic rock).

*MINERALS CHARACTERISTICS TO BE CLASSIFIED AS A MINERAL*
1. Naturally occurring
2. Solid
3. Inorganic
4. Geometric arrangement of its atoms
5. Chemical composition that can vary only according to  its specific limits

      *COMMON MINERALS*

*Quartz (SiO₂)* is most commonly known mineral. e.g Rose, Milky, Chart, Flint, Agate.

*Halite (NaCl)* is probably the most commonly used mineral and is found in most spice cabinets as table salt.

*PHYSICAL PROPERTIES OF MINERALS.*

1. *Hardness*: (vary from sample to sample of same mineral). e.g Magnetite ---- Hardness of 6. (5.5 - 6.5)

2. *Crystal form* is the geometric arrangement of plane(flat) surfaces on the outside of a mineral that reflect the internal crystallinity of the mineral.  Halite and Fluorite often has cubic crystal form. Corundum, Quartz and Calcite show different variations on the hexagonal crystal form.
Minerals without an external crystal form are referred to as *MASSIVE* (e.g. Chert, Limonite, e.t.c)

3. *Cleavage*: is the tendency of a mineral to break in a systematic way along planes of weakness determined by the type and strength of the chemical bonds between the atoms that make up the mineral.

4. *Fracture*:is the non- systematic and irregular way some minerals break. It is rough or uneven, unlike cleavage planes which are smooth and flat.
Conchoiddal fracture is a special kind of breakage that results in a curved parting surface. A homogeneous material that lack planes of weakness, equally strong in all directions.(e.g glass)

5. *Striations*: are very fine, parallel lines visible on the cleavage planes or crystal faces of some minerals due to their crystal structure and growth patterns.
Albite and Labradorite, both plagioclase feldspars---(1 cleavage plate). e.g. pyrite, quartz, garnet.
One direction cleavage: e.g. Biotite, Talc, Chlorite, Muscovite, Selenite, Gypsum

Two direction of cleavage: e.g. orthoclase and plagioclase

Three direction of cleavage:  e.g. Calcite

Four direction of cleavage:  e.g. Fluorite

Six direction of cleavage:  e.g. sphalerite


Comments

Post a Comment

Popular posts from this blog

📝 GNS101

-
21ST CENTURY LITERACY SKILLS  There are 4 language skills:  1. Listening 2. Speaking 3.Reading 4. Writing.  *The four skills are related to each other by two parameters:*  (a). the mode of communication: oral or written   (b) the direction of communication: receiving or producing the  message   *PRODUCTIVE SKILLS*  The productive skills are  1. SPEAKING 2. WRITING Learners doing these need to produce language.  These skills are contrasted with the *receptive skills* of listening and reading.    *RECEPTIVE SKILLS*  The receptive skills are  1. LISTENING 2. READING Learners do not need to produce language to do these: they receive and understand it.  They can be contrasted with the productive of speaking and writing.  These skills are sometimes erroneously described as   *passive skills,* as if they require no activity.  Note that all skills require some activity.   1. *LITERACY*  ...
Read more

📓 GNS101 WORD FORMATION (Morpheme)

-
WORD FORMATION (Morpheme)  *Word formation* refers to the way in which new words are formed in the basis of other words or morpheme.  And a morpheme is meaningful linguistic unit consisting of a word that cannot be divided into smaller meaning parts  _There is a difference between a morpheme and a word_  ▪️ *A word* can stand alone and can be meaningful but *a morpheme* can not always stand alone ▪️ *A word* can have 2 or more morphemes   ```LET ME GIVE EXAMPLE```   *RECONSTRUCT*    This is a word that has two morphemes (RE/CONSTRUCT).   When we have a sentence, it consists of clause. ⚡Clause consists of phrase ⚡Phrases consists of words ⚡And words consist of morpheme ⚡Morpheme consists of syllables   *Define a phrase*    Group of words without finite verb. So we can break this to phrase They/ might be thinking/of words/ and their meaning   Each of these phrases consists of one or two words   So words can be broken to...
Read more

📝GNS101. GOAL SETTING

-
GOAL SETTING AND TIME MANAGEMENT  *What is Time?* *Time* is a *limited* , *non-renewable* resource.  ❗❗❗. Note:  those key words must be there *What is Management?*  *Management* is the skilful handling or use of resources such as people (human capital), money,  materials and time  *What is Time Management?* *Time management* is an essential skill in the modern world where several activities have to be crammed into each day.  *There are several time management tools you can use.*  They are cheap and easily available. 🔘 a. *TIMETABLE* :  this is a tabulated list of the times at which certain events or activities are required to occur.  🔘b. *ORGANIZER* : This is a small portable calendar and data book used for planning, or a handheld  computerized device with a simple database for managing appointments and other information.  🔘 c. *TIMEPIECE* : A timepiece is any instrument for recording or showing the time, especially one tha...
Read more