UGC NET Geography 1

The north-pole lies with in the Arctic Ocean whereas south-pole is located within Antartic Continent. Which of the following theory uses this phenomenon as a supportive argument ?

(A) Theory of Isostasy

(B) Theory of Plate Tectonics

(D) Tetrahedral Theory

The answer is **(B) Theory of Plate Tectonics**.

The theory of plate tectonics states that the Earth's surface is made up of a number of large plates that are constantly moving. The North Pole lies within the Arctic Ocean because the Arctic Ocean is located on a plate that is moving away from the North Pole. The South Pole, on the other hand, is located within Antarctica because Antarctica is a continent that is not moving.

The other theories listed are not supportive of this phenomenon. The theory of isostasy states that the Earth's crust is balanced by the underlying mantle, so the North Pole would not be located in an ocean if this theory were correct. The theory of convective current theory states that the Earth's mantle is heated from below and that this heat causes the mantle to move, but this theory does not explain why the North Pole is located in an ocean and the South Pole is located on a continent. The tetrahedral theory is not a scientific theory and is not supported by evidence.

**Explanation of other theories:**

* **Theory of Isostasy** states that the Earth's crust is balanced by the underlying mantle. This means that the weight of the crust is supported by the mantle, so the crust does not sink into the mantle. The North Pole is located in an ocean because the crust in this area is relatively thin. The mantle is therefore able to push up the crust, creating an ocean.

* **Theory of Convective Current Theory** states that the Earth's mantle is heated from below and that this heat causes the mantle to move. The mantle is a layer of hot, solid rock that lies below the Earth's crust. The heat from the Earth's core causes the mantle to move in a convective current. This means that the mantle is constantly circulating, with hot material rising to the surface and cooler material sinking to the bottom. The convective current theory does not explain why the North Pole is located in an ocean and the South Pole is located on a continent.

* **Tetrahedral Theory** is not a scientific theory and is not supported by evidence. This theory states that the Earth is shaped like a tetrahedron, with the North Pole at one point of the tetrahedron and the South Pole at another point. The theory also states that the Earth's crust is made up of four plates that are constantly moving. However, there is no scientific evidence to support this theory.

Therefore, the theory of plate tectonics is the best explanation for why the North Pole lies within the Arctic Ocean and the South Pole is located within Antarctica.

🌍

Comments

Remote Sensing Technology

Remote sensing is a rapidly evolving geospatial technology used to collect information about the Earth's surface and atmosphere without direct physical contact . It involves detecting and measuring electromagnetic radiation (EMR) reflected or emitted from objects using sensors mounted on satellites, aircraft, or drones. Remote sensing systems are fundamentally classified based on (1) the energy source used for illumination and (2) the region of the electromagnetic spectrum utilized for sensing . 1. Types of Remote Sensing Based on Energy Source Remote sensing systems are commonly categorized according to whether the sensor generates its own energy or relies on naturally available radiation . Passive Remote Sensing Principle: Passive remote sensing relies on natural sources of electromagnetic energy , primarily solar radiation reflected from the Earth's surface or thermal radiation emitted by objects. Operation: Most passive sensors operate during daylight when sunlight is av...

Spectral Signature vs. Spectral Reflectance Curve

Spectral Signature A spectral signature is the unique pattern in which an object: absorbs energy reflects energy emits energy across different wavelengths of the electromagnetic spectrum. ✔ Key Points Every natural and man-made object on Earth interacts with sunlight differently. These interactions produce a distinct pattern , just like a "fingerprint". Sensors on satellites record these patterns as digital numbers (DN values) . These patterns help to identify and differentiate objects such as vegetation, soil, water, snow, buildings, minerals, etc. ✔ Examples of Spectral Signatures Healthy vegetation → High reflectance in NIR , strong absorption in red Water → Strong absorption in NIR and SWIR , low reflectance Dry soil → Gradual increase in reflectance from visible to NIR Snow → High reflectance in visible , low in SWIR ✔ Why Spectral Signature Matters It allows: Land cover classification Chan...

History of GIS

1. 1832 - Early Spatial Analysis in Epidemiology: - Charles Picquet creates a map in Paris detailing cholera deaths per 1,000 inhabitants. - Utilizes halftone color gradients for visual representation. 2. 1854 - John Snow's Cholera Outbreak Analysis: - Epidemiologist John Snow identifies cholera outbreak source in London using spatial analysis. - Maps casualties' residences and nearby water sources to pinpoint the outbreak's origin. 3. Early 20th Century - Photozincography and Layered Mapping: - Photozincography development allows maps to be split into layers for vegetation, water, etc. - Introduction of layers, later a key feature in GIS, for separate printing plates. 4. Mid-20th Century - Computer Facilitation of Cartography: - Waldo Tobler's 1959 publication details using computers for cartography. - Computer hardware development, driven by nuclear weapon research, leads to broader mapping applications by early 1960s. 5. 1960 - Canada Geograph...

Raster Data Model

A raster data model represents geographic space as a grid of cells (called pixels ). Think of it like a chessboard covering the Earth. Each square = cell / pixel Each cell contains a value That value represents information about that location Example: Elevation = 245 meters Temperature = 32°C Land use = Forest The grid is arranged in: Rows Columns This structure is called a matrix . GRID Model (Cell-Based Matrix Model) 🔹 Concept The GRID model is the most common raster structure used in GIS for spatial analysis . It is mainly used for: Continuous data (data that changes gradually) Sometimes discrete/thematic data 🔹 Structure A 2D matrix (rows × columns) Each cell stores one numeric value Integer (whole number) Float (decimal number) 🔹 Key Terminologies Cell Resolution → Size of each pixel (e.g., 30m × 30m) Spatial Resolution → Level of detail DEM (Digital Elevation Model) → Elevation grid Raster Calculator → Tool for mathematical operations Overlay Analysis → Combining mu...

Model GIS object attribute entity

These concepts explain different ways of organizing, storing, and representing geographic information in a Geographic Information System (GIS) . They include database design models (ER model), data structure models (Object and Attribute models), and spatio-temporal representations that integrate location, entities, and time . Together, they help GIS manage both spatial data (where things are) and descriptive information (what they are and how they change over time) . 1. Object-Based Model (Object-Oriented Data Model) The Object-Based Model treats geographic features as independent objects that combine spatial geometry and descriptive attributes within a single structure. Core Concept: Each geographic feature (such as a building, road, or river ) is represented as a self-contained object that stores both: Geometry – location and shape (point, line, polygon) Attributes – descriptive properties (name, type, length, capacity) Unlike older georelational models , which stored spatial ...

Vineesh V, Geography

Search This Blog