DSC-152: Section-B (Earth and Earth Surface Processes)

Practical 6: Study of model for continental drift

Objective

To study and interpret a model (physical or digital) illustrating the breakup of Pangaea and the subsequent movement of continents.

Procedure

1. Observe the provided model of Pangaea (approx. 250 million years ago - Ma). Identify the landmasses that would become modern continents.
2. Observe the model showing the first split into Laurasia (north) and Gondwanaland (south).
3. Trace the movement of key landmasses, particularly the "jigsaw fit" of South America and Africa.
4. Note the northward drift of the Indian subcontinent and its eventual collision with the Eurasian plate, which formed the Himalayas.

Observation

Draw simple, labeled diagrams for at least three stages:

1. Pangaea (Permian, ~250 Ma): A single supercontinent.
2. Laurasia & Gondwanaland (Jurassic, ~150 Ma): The Tethys Sea separates the two new supercontinents.
3. Present Day: Continents in their current positions.

List the key pieces of evidence for continental drift:

• Jigsaw Fit: e.g., South America and Africa.
• Fossil Evidence: e.g., *Mesosaurus* (a freshwater reptile) found in both Brazil and South Africa.
• Rock Evidence: Matching mountain ranges (e.g., Appalachians in USA and Caledonian in Scotland).
• Glacial Evidence: Glacial scratches (striations) found in warm regions like India, Africa, and Australia.

Practical 7: Identification of sedimentary and metamorphic rocks

Objective

To identify given hand specimens of sedimentary and metamorphic rocks based on their physical properties.

Materials

• Hand specimens of rocks (e.g., Sandstone, Limestone, Shale, Gneiss, Marble, Slate)
• Hand lens (magnifying glass)
• Dilute HCl (hydrochloric acid) in a dropper bottle
• Streak plate (unglazed porcelain)

Procedure

For each rock specimen, observe and record the following properties:

1. Color: The overall color of the rock.
2. Texture:
   • Sedimentary: May be "clastic" (made of visible grains/fragments, e.g., Sandstone) or "crystalline" (e.g., chemical Limestone). Often feels gritty.
   • Metamorphic: Almost always crystalline. Can be "foliated" (shows layers/bands, e.g., Gneiss, Slate) or "non-foliated" (no bands, e.g., Marble, Quartzite).
3. Key Features:
   • Sedimentary: Look for layers (stratification), fossils, or visible cemented grains.
   • Metamorphic: Look for foliation (bands), a "stretched" appearance, or a crystalline, sparkly texture (e.g., from mica).
4. Acid Test: Place one drop of dilute HCl on the rock. If it fizzes, it contains calcium carbonate. This is the key test for Limestone (sedimentary) and Marble (metamorphic).

Observation Table

Practical 8: Study and interpretation of Geological time scale

Objective

To study a chart of the Geological Time Scale and learn to identify the major divisions and the key life forms that appeared or dominated in each.

Procedure

1. Observe the provided GTS chart. Note the hierarchy: Eon > Era > Period > Epoch.
2. Identify the two major Eons: Precambrian (covers ~90% of Earth's history) and Phanerozoic (the "Eon of visible life").
3. Focus on the three Eras of the Phanerozoic Eon:
   • Paleozoic Era: "Age of Invertebrates" (or "Age of Fishes")
   • Mesozoic Era: "Age of Reptiles" (dinosaurs)
   • Cenozoic Era: "Age of Mammals"
4. For each Era, identify one or two major events (e.g., Mesozoic -> Triassic, Jurassic, Cretaceous periods; dominance and extinction of dinosaurs).

Observation

Create a simplified summary table:

Practical 9: Study of Topographic map

Objective

To learn how to read and interpret the basic features of a topographic map, especially contour lines.

Procedure

Using a sample toposheet, identify the following features:

1. Map Symbols (Legend): Find the legend. Identify symbols for man-made features (roads, buildings, temples) and natural features (rivers, vegetation).
2. Scale: Find the map scale (e.g., 1:50,000, which means 1 cm on the map = 50,000 cm (or 500m) in reality).
3. Contour Lines:
   • Contour Interval: Find the stated interval (e.g., "Contour Interval 20 meters"). This is the vertical distance between any two adjacent lines.
   • Index Contours: These are the thicker, labeled lines that show the actual elevation (e.g., "500m").
4. Interpreting Landforms:
   • Steep Slope: Contour lines are very close together.
   • Gentle Slope: Contour lines are far apart.
   • Hilltop/Peak: A series of closed, concentric contour lines.
   • Valley/River: Contour lines form a "V" shape. The "V" always points uphill, or upstream.

Observation

Draw simple diagrams illustrating how contour lines represent:

• A steep slope vs. a gentle slope.
• A conical hill.
• A river valley.

Practical 10: Study of landscapes of urban, semi-urban and rural areas

Objective

To compare and contrast the key landscape features of urban, semi-urban, and rural areas, often using maps, satellite imagery, or a field visit.

Procedure

For each of the three landscape types, analyze the following components:

1. Patches: The dominant "patches" or land-cover types (e.g., buildings, forests, farm fields, water).
2. Matrix: The most extensive and connected land-cover type that forms the "background" (e.g., concrete in urban, farmland in rural).
3. Corridors: Linear features that connect patches (e.g., roads, rivers, hedges).
4. Permeability: How much of the surface is "impermeable" (e.g., concrete, pavement) vs. "permeable" (e.g., soil, grass).

Observation Table