Vineesh V, Geography

India in the Plate Tectonic Framework Geological Journey ~150 million years ago – Part of Gondwanaland with Africa, Antarctica, Australia, and South America. ~120 million years ago – Broke away and drifted north across the Tethys Ocean at exceptional speed (~15–20 cm/year). ~50 million years ago – Collided with the Eurasian Plate, closing the Tethys Ocean. Present – Still converging with Eurasia (~5 cm/year), causing active mountain building and earthquakes. Tectonic Plate of India Indian Plate – Once part of Gondwanaland; now includes the Indian subcontinent and surrounding oceanic crust. Collision with Eurasia – Caused the Himalayan Orogeny and uplift of the Tibetan Plateau. Ongoing Movement – Himalayas rise ~5 mm/year; frequent seismic events occur. Current Tectonic Setting North – Convergent boundary with Eurasian Plate → Himalayan uplift, seismicity (e.g., Nepal 2015 earthquake). West – Interaction with Arabian Plate along Ow...

1. Global Plate Tectonics  The theory of Plate Tectonics explains how the Earth's lithosphere (the rigid outer shell) is broken into large pieces called plates . Plates : These plates float over the softer, semi-molten layer beneath, called the asthenosphere . Movement : Driven by heat from Earth's interior (mantle convection, ridge push, slab pull), plates move a few centimetres per year — about the speed your fingernails grow. Boundaries : Where plates meet, we get different interactions: Divergent boundaries – plates move apart (mid-ocean ridges, new crust formation). Convergent boundaries – plates collide (mountains, subduction zones). Transform boundaries – plates slide past each other (earthquakes). Why it matters: This movement shapes continents, mountains, volcanoes, ocean basins, and earthquakes. 2. India's Place in Global Plate Tectonics India's geologic story is one of the most dramatic and fast-moving continental j...

1. Surface Analysis 🗺️ This is when we try to understand and visualize how a value changes across a surface (like land). The values might be temperature, rainfall, elevation, pollution levels, etc. We often start with only some points where we know the value, but we want to guess the values everywhere in between. 2. Interpolation 📍➡️📍 Interpolation is a way of estimating unknown values between known points. Imagine you know the temperature at a few weather stations, but you want to know the temperature everywhere in between. GIS uses math to "fill in the blanks" between the points. 3. IDW (Inverse Distance Weighted) 🎯 One popular interpolation method. The idea: Points that are closer to you have more influence than points farther away. Example: If you're standing between two rain gauges, the closer one's reading will affect your estimated rainfall more than the farther one. "Inverse Distance" means: The ...

Think of your vector data (points, lines, polygons) like shapes drawn on a transparent sheet. Geoprocessing is just cutting, joining, or comparing those shapes to get new shapes or information. 1. Clipping ✂️ Imagine you have a big map and you only want to keep a part of it (like cutting a photo into a smaller rectangle). You use another shape (like the boundary of a district) to "clip" and keep only what is inside. Result: Only the data inside the clipping shape remains. 2. Erase 🚫 Opposite of clipping. You remove (erase) the area of one shape from another shape. Example: You have a city map and want to remove all the park areas from it. 3. Identify 🔍 This checks which features from one layer fall inside (or touch) another layer. Example: Identify all the schools inside a flood zone. 4. Union 🤝 Combines two shapes together and keeps everything from both. Works like stacking two transparent sheets and redrawing t...

  Major Terms and Regions Explained 1. Indian Shield The Indian Shield refers to the ancient, stable core of the Indian Plate made of hard crystalline rocks. It comprises Archean to Proterozoic rocks that have remained tectonically stable over billions of years. Important Geological Features and Regions ▪️ Ch – Chhattisgarh Basin A sedimentary basin part of the Bastar Craton . Contains rocks of Proterozoic age , mainly sedimentary. Important for understanding the evolution of central India. ▪️ CIS – Central Indian Shear Zone A major tectonic shear zone , separating the Bundelkhand and Bastar cratons . It records intense deformation and metamorphism . Acts as a suture zone , marking ancient tectonic collisions. ▪️ GR – Godavari Rift A rift valley formed due to stretching and thinning of the Earth's crust. Associated with sedimentary basins and hydrocarbon resources . ▪️ M – Madras Block An Archean crustal block in...

What is Overlay Analysis ? Overlay means placing one layer on top of another in GIS to see how they are related. Imagine putting a transparent sheet of roads on top of a map of forests — that's overlay! 1. Point in Line Points are single locations (like bus stops). Lines are long features (like roads or rivers). "Point in Line" means checking which points lie on or near a line . ✅ Example: You have a map of bus stops (points) and roads (lines). You check which bus stops are on which roads . 2. Point in Polygon Polygon is an area (like a city, park, or forest). Point in Polygon means checking which points are inside an area . ✅ Example: You have schools (points) and a map of city boundaries (polygons). You want to see which schools are inside which city . 3. Line in Polygon Now you're checking which lines pass through or are inside areas . ✅ Example: You have rivers (lines) and forests (polygons). You w...

 What is Proximity Analysis ? Proximity means "how close or far something is." So, Proximity Analysis in GIS means finding out how near or far one thing is from another on a map.  What is Buffer Analysis ? Buffer means a zone (area) around something . In GIS: If you draw a circle around a school with 1 km radius , that area is called a buffer . It shows which houses or roads are within 1 km of the school. ✅ Example : You want to find all houses within 500 meters of a river . GIS will create a buffer zone (a shaded area) around the river, and then highlight all houses inside it. What is Multi Buffer Concept ? Instead of just one buffer zone , you can make many buffer zones around a place. ✅ Example : Let's say you make 3 buffer zones around a hospital: 0–1 km (red) 1–2 km (orange) 2–3 km (yellow) Now, you can: See which areas are very close (red), Which are a bit far (orange), And which are farther away (...

What is Tabular Data? Tabular data is data that looks like a table — rows and columns, just like in Excel. Each row is a different place (like a city or a school), and each column has information about that place (like population, name, rainfall, etc.). What is Vector Data? Vector data is the way we draw things on a map using points (like a bus stop), lines (like a road), or polygons (like a park or city area). Now, how do we map tabular data in GIS? Imagine you have a table like this: City Name Population Literacy Rate Palakkad 1,30,000 92% Kochi 6,00,000 95% And in GIS, you have a map of Kerala showing where Palakkad and Kochi are as points (vector data). In GIS, you "join" the table with the map. GIS connects the rows in the table to the points on the map using a common link , like the city name. Once they are linked: You can see the data on the map . You can color the cities based on population or literacy. You can make graphs or charts ...

Spatial relationships show how things are located in relation to each other on a map. Here are some examples: Relationship Type Example Near A school is near a hospital Inside A tree is inside a park Touching Two countries are touching at their borders Overlapping A flood zone overlaps with farmland Connected One road is connected to another road Spatial Query? A spatial query is a question that asks about the location or relationship between features on a map. It's different from a regular query (which asks about data in a table ). A spatial query asks about where things are and how they relate to each other. Examples of Spatial Queries: "Which schools are within 1 km of the main road?" "Find all rivers that cross the highway." "Show all houses inside the flood zone." "Which villages are near a hospital?" GIS uses this information to highlight or select features based on their spatial relat...

In GIS, vector data is a way of representing the world using points, lines, and polygons . A point shows a single location (like a school). A line shows things like roads or rivers. A polygon shows areas like parks, lakes, or countries. Each of these features has extra information called "attributes." Attribute Data? Think of attribute data like a table full of details about each feature on a map. For example, if you have a map of schools (points) : ID Name Type Students 1 City High Government 800 2 St. Mary's Private 650 3 Sunrise Acad Government 950 Each row is one school (point), and each column is an attribute (name, type, number of students, etc.). Query? A query means asking questions using the attribute data. In GIS, queries help us find only the information we need from the map. For example: "Show me all Government schools." "Find schools with more than 800 students ." "Which rivers ...