Science Study Guide

1. Key Glacial Terms Explained

Building on your notes, here is how these features actually form:

• Glacial Striations: As glaciers move, they act like giant sheets of sandpaper. Rocks and gravel frozen into the bottom of the ice scrape against the bedrock, leaving behind these long, parallel grooves. They are like "fingerprints" that tell geologists which direction the ice was moving.

• Glacial Till: Unlike rivers, which sort sediment by size (pebbles here, sand there), glaciers are messy. Till is "unsorted," meaning it’s a jumbled mix of everything from tiny clay particles to large boulders. It is very nutrient-rich, which is why areas with old glacial deposits often have great farmland.

• Glacial Erratic: These are the "hitchhikers" of the geological world. A glacier can carry a massive rock for hundreds of miles. When the ice melts, it drops the rock in a new area where the local geology is completely different (e.g., a granite boulder sitting in a field of limestone).

2. Claim: The U-Shaped Valley

The photo shows a classic example of a U-shaped valley (also called a glacial trough).

Claim: This landform was created by glacial erosion.

Evidence & Reasoning:

• The "U" Shape: Unlike rivers, which cut narrow V-shaped valleys, glaciers are wide and heavy. They scour both the bottom and the sides of a valley, carving out a broad, flat floor and steep, vertical walls.

• Scale: The valley is massive and deep, indicating it was carved by a force much larger and more powerful than a standard river.

• Truncated Spurs: Notice how the ridges of the mountains seem to be "cut off" rather than gently sloping into the valley. This happens when the moving ice shears off the ends of mountain ridges.

3. How Glaciers Change the Land

You correctly noted that glaciers move slowly and erode the land. To add to that, they erode in two specific ways:

1. Plucking: The glacier freezes onto pieces of rock and literally "plucks" them out of the ground as it moves.

2. Abrasion: The rocks stuck in the ice grind against the ground like a file.

Something New: Moraines

Since you have Till on your sheet, you should know about Moraines. These are the ridges or mounds of till left behind at the edges or the front of a glacier. They act like a "debris line" showing the furthest point the glacier reached before it started melting.

1. Physical & Biological Weathering

Weathering is the breaking down of rocks in place.

• Heat Expansion: Rocks expand when they get hot and shrink when they cool. Over time, this constant "pulsing" causes the outer layers of the rock to crack and peel off like an onion (also called exfoliation).

• Root Wedging: This is biological weathering. A tiny seed falls into a crack in a rock. As the plant grows, the roots get thicker and act like a powerful wedge, eventually splitting the rock apart.

• Lichen Growth: Lichens (the crusty green/gray stuff on rocks) produce weak acids. These acids slowly dissolve the minerals in the rock, weakening the surface.

2. Parts of a River

Think of a river as a conveyor belt moving water and sediment from high ground to low ground.

3. Erosion, Weathering, and Deposition

This section focuses on how water moves material.

Where do weathering and erosion occur most?

• Location: The River Source or the Upper Course (where it's steep).

• Why? Gravity makes the water move very fast here. High-energy, fast-moving water has more power to wear down rocks (weathering) and carry away heavy sediment (erosion).

Where does deposition occur most?

• Location: The River Mouth or Inside Meanders (curves).

• Why? Deposition happens when water slows down. When the river hits a flat area or a large body of water (the mouth), it loses the energy needed to carry sand and rocks, so it "drops" them, often forming a delta.

Variables that impact these processes:

1. Velocity (Speed): Faster water erodes more; slower water deposits more.

2. Gradient (Slope): Steeper land makes water flow faster.

3. Volume (Discharge): A flooded river has much more power to erode and carry large boulders than a dried-up stream.

Pro-tip for your notes:
Rivers usually start V-shaped near the source (because they cut downward quickly) and become wide and flat near the mouth.

1. The Water Cycle

The cycle is driven by the sun's energy. It’s a "closed system," meaning the water we have now is the same water that was here during the time of the dinosaurs!

• Evaporation (Liquid to Vapor): The sun heats up liquid water in oceans and lakes, turning it into invisible gas (water vapor) that rises into the air.

• Condensation (Vapor to Liquid): As that gas rises, it cools down and turns back into tiny liquid droplets, which bunch together to form clouds.

• Precipitation: When those droplets in the clouds get too heavy, they fall back to Earth as rain, snow, sleet, or hail.

2. Processes That Shape Earth

Think of these three as a "destruction and construction" team:

3. Types of Weathering

You have the definitions for Frost Wedging and Abrasion started; here is how to round them out:

• Frost Wedging:

  • Description: Water gets into cracks in rocks. When it freezes, it expands (by about 9%), acting like a lever that pushes the rock apart until it snaps.

  • Visual clue: Think of jagged, broken rocks at the bottom of a mountain.

• Abrasion:

  • Description: This is the "sandblasting" effect. When wind or water carries sand and pebbles, they rub against larger rocks, grinding them down.

  • Visual clue: Think of smooth, rounded river stones or "mushroom" shaped rocks in the desert.

• Salt water weathering - If a rock is near saltwater, the water can penetrate through the surface of the rock, the water will then evaporate, leaving behind salt crystals. These crystals can grow over time, exerting pressure on the rock, which eventually leads to further disintegration and erosion, and the rock breaking apart.

• Heat expansion - As rock is heated/cooled it expands and contracts, which can create stress within the rock structure. This repeated cycle of expansion and contraction can lead to cracking and fragmentation, especially in environments with extreme temperature variations, and shedding of its outer layer (deserts/wildfires)

• Root wedging - A tree or plant root grows into the cracks of rocks, slowly causing the rock to break as roots grow

• Lichen growth - Crusts are formed on rocks, from the growth of algae and fungi; causing the rocks to break down

Add-on Info: Chemical Weathering

Your notes mention "chemical" under Weathering. This is different from the physical "breaking" above.

• Example: Oxidation (Rust). When iron in rocks reacts with oxygen and water, the rock turns red and becomes soft and crumbly. It’s like the rock is "rotting" rather than being smashed.

1. Key Definitions

2. Comparing Gravel, Sand, and Silt

Think of this like a race. The larger the "tunnels" between the particles, the faster the water wins.

• Fastest Infiltration: Gravel

  • Why? Because the pieces of gravel are large and irregular, they create massive gaps (pores) that are well-connected. Water can pour right through without much resistance.

• Slowest Infiltration: Silt

  • Why? Silt particles are tiny and pack together very tightly. The "tunnels" are so small and narrow that it takes much longer for water to squeeze its way through.

3. The "Porosity Trap" (Add-on Info)

Here is a trick question teachers love: Does a bucket of large rocks have more porosity than a bucket of small sand?

Actually, if the particles are all the same shape (spheres), the porosity is often the same. Both can hold roughly the same amount of water in total. The big difference is permeability—the gravel will always let water pass through much faster because the individual gaps are bigger.

Deep Dive:
In nature, Clay actually has very high porosity (lots of tiny holes), but it is impermeable because the holes are so small and flat that water gets stuck and can't flow. This is why farmers don't like clay-heavy soil; it stays "waterlogged" and doesn't drain.

1. Water's Movement Diagram

This web shows that Earth doesn't just have water; it moves it around constantly.

• What does this show?

  1. The Water Cycle: It illustrates how water is never "stuck" in one place; it's always on the move.

  2. Reservoirs: It shows the main places water is stored (Glaciers, Oceans, Lakes, Atmosphere).

  3. Phase Changes: It represents water changing from a solid (glacier) to a liquid (ocean) to a gas (atmosphere).

• Does the amount of water change? No. As you noted on a previous page, Earth is a closed system. We aren't getting "new" water from space, and it isn't leaving. It just keeps changing its "outfit" (solid, liquid, gas).

2. Water Flow on the Mountain

Looking at the diagram of the mountain zones:

• How it flows: Water flows downward from the peak (snow line) toward the forest at the bottom.

• Why? Gravity. Gravity is the primary force that pulls water from high elevations to low elevations. It will follow the path of least resistance, carving out the river channels you studied earlier.

3. Definitions: The Mechanics of Movement

4. The "Add-On": Infiltration vs. Runoff

This is a great way to connect this page to your previous one on Permeability:

• If the ground is permeable (like gravel), you get high Infiltration and low Runoff.

• If the ground is impermeable (like solid rock or a paved parking lot), you get zero infiltration and high Runoff. This is exactly why cities have to build storm drains—to handle all the runoff that can't soak into the concrete!

1. The Three Main Types of Rock

The diagram shows the big three. Think of them like this:

• Igneous: Born from fire (cooled magma or lava).

• Sedimentary: Born from recycling (pieces of other rocks glued together).

• Metamorphic: Born from change (existing rocks squeezed and cooked until they transform).

2. Breaking Down the Processes

Here is the key to the numbered steps on your worksheet:

3. The "Add-On": Deep Time

The one thing this diagram doesn't show is how long this takes.

• A "Fast" Rock: Lava can cool into Igneous rock in days or weeks.

• A "Slow" Rock: It can take millions of years for sediment to turn into rock, or for a rock to travel deep enough into the Earth to melt.

Pro-Tip: Fossils

If you ever see a question asking where to find a fossil, it is almost always in Sedimentary Rock. The heat and pressure required to make Igneous or Metamorphic rocks would destroy any plant or animal remains!

Process Check (Bottom Left)

You nailed these! Here is a slightly more detailed way to think about them:

1. Weathering/Erosion: Rocks break down into "crumbs."

2. Weathering/Erosion: Even sedimentary rocks can be broken back down.

3. Compaction & Cementation: The "Lithification" step—turning crumbs into solid stone.

4. Heat & Pressure: Like baking a cake; the ingredients change without melting.

5. Melting: Turning solid back to liquid magma.

6. Weathering/Erosion: Metamorphic rocks aren't safe from the wind and rain either!

7. Heat & Pressure: Turning igneous rock into metamorphic rock.

8. Melting: Igneous rock melting back into magma.

9. Cooling: Magma hardening into solid rock.

2. Labeling the Diagram (Top Right)

The diagram on the right uses arrows to show the same "loop." Here are the labels you need:

• Magma

  Igneous Rock: The process is Cooling and Hardening.

• Igneous

  Sediment: The process is Weathering and Erosion.

• Sediment

  Sedimentary Rock: The process is Compaction and Cementation.

• Sedimentary

  Metamorphic Rock: The process is Heat and Pressure.

• Metamorphic

  Magma: The process is Melting.

3. "The Shortcut" Add-on

Notice how there are arrows cutting across the middle of the circle? Those are the "shortcuts":

• Igneous directly to Metamorphic: If a volcano is buried by a shifting tectonic plate, it can become metamorphic without ever becoming sediment first.

• Sedimentary directly to Sediment: A rock layer can be pushed up to the surface and start eroding away before it ever has a chance to become metamorphic.

Fun Fact: The Obsidian (black volcanic glass) you might see in games or jewelry is an igneous rock that cooled so fast that crystals didn't even have time to grow!

Igneous rocks

Intrusive

Characteristics and properties - Larger grains, individual grains, cools slowly, coarse texture

Formation - Inside earth, magma trapped causes cools over millions of years

Extrusive

Characteristics and properties - fine grained, glossy, bubbly, cools quickly, smooth(er) texture

Formation- Cools quick, and above the earth’s surface

Sedimentary

Clastic

Characteristics and properties - Distinctive layering, made of pre-existing rocks, can be broken easily

Formation - Wasted/eroded material gets deposited, and becomes buried deeply over time it becomes compacted/cemented

Biological

Characteristics and properties - distinctive layering, made of dead living things, and can be broken easily

Formation - same as clastic

Metamorphic

Foliated

Characteristics and properties - strongest type of rock, striped/layered

Formation - Started out from other rock, but changed from original. Form when rocks are subjected to high heat, pressure,

1. How Sedimentary Rocks Form

The graphic on the left shows a process called Lithification (turning stone into stone). You can explain the graphic using these three steps:

1. Deposition: Sediments (sand, mud, pebbles) settle at the bottom of a body of water in flat layers.

2. Compaction (Burial): As more layers pile on top, the weight of the new layers "squishes" the bottom layers, squeezing out air and water.

3. Cementation: Dissolved minerals act like natural glue, filling the tiny spaces between the sediment and hardening everything into a solid rock.

Your written summary at the bottom: "These rocks are formed when existing rocks are weathered down and then transported (eroded). After being deposited in layers, the weight of the top layers compacts them, and minerals cement them together over time."

2. Process Deep-Dive (The Chart)

Here is a breakdown of the "Describe the Process" section:

• Heat & Pressure: Occurs deep underground. It makes rocks denser and can align minerals into bands (foliation) without melting them. Think of it like squishing a marshmallow—it changes shape but stays solid.

• Melting: Rocks turn into magma. This happens when they are pushed so deep into the Earth's mantle that the temperature exceeds the rock's melting point.

• Cooling: As magma or lava loses heat, it undergoes crystallization. The slower it cools, the larger the crystals (like the "sparkles" in granite).

• Weathering & Erosion: Weathering breaks it (physical or chemical); Erosion takes it (moves it via wind, water, or gravity).

• Compacting & Cementing: Compacting is the squeeze; Cementing is the glue.

3. The "Add-On": Layering (Law of Superposition)

Looking at the "Layers of Sediment" diagram, there’s a secret rule geologists use: The Law of Superposition.

• Unless something crazy happens (like an earthquake flipping the land), the layer on the bottom is always the oldest, and the layer on the top is the youngest. It’s like a laundry basket; the clothes you wore on Monday are at the bottom, and today's are on top.

Wait—did you notice?
In your notes for "Heat & Pressure," you mentioned it relates to metamorphism. This is a great connection! That is exactly how an igneous rock "skips the line" to become a metamorphic rock.

1. Foliated Metamorphic Rock

This is the "striped" or "banded" version. You can see these clear lines in the top photos (like the Gneiss on the top left).

• Characteristics and Properties:

  • Striped/Layered: Contains visible parallel layers or bands of minerals.

  • Pressure-driven: The minerals align themselves perpendicular to the direction of the pressure.

  • Examples: Gneiss (pronounced "nice"), Slate, and Schist.

• Formation: When a rock is squeezed from specific directions, the mineral grains become flattened and line up in a pattern, much like squeezing a deck of cards.

2. Non-Foliated Metamorphic Rock

This is the "solid" or "chunky" version. You can see these in the bottom photos (like the Quartzite or Marble).

• Characteristics and Properties:

  • Massive/Blocky: No layers or bands are visible.

  • Uniform Appearance: It looks more like a single solid mass of interlocking crystals.

  • Examples: Marble (formed from limestone) and Quartzite (formed from sandstone).

• Formation: These form when heat is the primary factor (like being near a magma chamber) or when the rock is made of only one mineral. Since there isn't uneven pressure, the crystals grow larger and lock together but don't line up in stripes.

3. The "Add-On": Parent Rocks

Every metamorphic rock has a "parent" (the original rock it used to be before it was squeezed/heated).

Cool Fact: Marble is popular for statues because it is non-foliated. Because it doesn't have layers (foliation), it won't split along a "grain" when a sculptor carves it, making it much more durable for art!

Would you like to know how to use acid (like vinegar) to tell the difference between Marble and Quartzite, even though they look similar?

1. Clastic Sedimentary Rock

These are the "rock-fragment" rocks. The word "clastic" comes from a Greek word meaning "broken."

• Formation: They form from the physical pieces (clasts) of other rocks that have been weathered down. These fragments are carried by water, wind, or ice and then cemented together.

• Characteristics and Properties:

  • Categorized by Size: Geologists name them based on how big the pieces are (e.g., shale is tiny mud, sandstone is sand, conglomerate is large pebbles).

  • Visible Grains: You can often see the individual bits that make up the rock.

• Visual Examples:

  • Top Left (Visual #2): Likely a Conglomerate. Notice the rounded pebbles—this means the pieces traveled a long way in a river, getting "tumbled" smooth before being glued together.

  • Top Right (Visual #1): Likely a Breccia. Notice the sharp, angular edges. These pieces didn't travel far; they were broken and buried almost immediately.

2. Biological Sedimentary Rock

Sometimes called Organic sedimentary rocks, these are the "life-based" rocks.

• Formation: They form from the accumulated remains of living things. This could be shells from sea creatures, skeletons, or even compressed plant matter.

• Characteristics and Properties:

  • Fossil-Rich: You can often see actual shells, leaf imprints, or skeletons embedded in the rock.

  • Chemical Reaction: Because shells are made of calcium carbonate, many of these rocks will "fizz" if you drop a little vinegar on them.

• Visual Examples:

  • Bottom Right: This is a classic example of Coquina. It looks like a "granola bar" made entirely of crushed sea shells.

  • Bottom Left: Likely a Fossiliferous Limestone, where shells and coral have been compacted into solid stone.

3. The "Add-On": Chemical Sedimentary Rocks

To finish your set, there is a third category not on this page: Chemical Sedimentary Rocks.
These don't form from pieces or life, but from evaporation.

• Example: When a sea dries up, it leaves behind minerals like Rock Salt or Gypsum. These minerals "precipitate" out of the water, crystallizing into rock.

Pro-Tip for your notes:
If you look closely at a clastic rock and the pieces are rounded, you know there was a river nearby. If they are sharp, you might be looking at the site of an ancient landslide!

1. Igneous Rocks: Intrusive vs. Extrusive

The difference between these two is all about location and cooling speed.

Intrusive Igneous Rock (The "Inside" Rocks)

• Formation: These form underground as magma cools slowly deep within the Earth's crust.

• Characteristics: Because they cool so slowly, the crystals have time to grow very large. They have a coarse-grained (speckled) texture.

• Visuals: The top two photos (like Granite and Diorite) show these large, visible mineral grains.

Extrusive Igneous Rock (The "Exit" Rocks)

• Formation: These form on the surface after a volcano erupts and the lava cools quickly in the air or water.

• Characteristics: Because they cool so fast, crystals don't have time to grow. They are fine-grained, glassy, or vesicular (full of air bubbles).

• Visuals:

  • Bottom Right: Obsidian. It cooled so instantly it became smooth, black glass.

  • Bottom Left: Scoria or Pumice. The "holy" texture comes from gas bubbles trapped in the lava as it hardened.

2. River Anatomy Review

Looking at the diagram on the right, you can match the letters to the parts of the river:

• A: River Source (The high point in the mountains where the water begins).

• B: River Channel (The main "pathway" the water flows through).

• C: River Bank (The land along the sides that holds the water in).

• D: River Mouth (The end point where the river flows into a larger body of water, like an ocean).

3. The "Add-On": Crystal Size Rule

If you are ever looking at a mystery rock, remember this simple rule: Bigger Crystals = Deeper Cooling.

• If you see "sparkles" or chunks of color (like in a granite countertop), it’s Intrusive.

• If it looks like a solid color, a piece of glass, or a sponge, it’s Extrusive.

Fun Fact: Pumice is an extrusive rock that is so full of air bubbles (vesicles) that it is the only rock in the world that can actually float on water!