Earth Systems Science · Module 1

What is the ground under your feet made of?

Under Houston there is no bedrock to dig down to: just hundreds of metres of loose sediment. Almost every grain was carried here from somewhere else.

These slides give you the science, math, and data to explain how.

Start → Jump to my project Formula sheet
The ground under a Houston campus, top to bottom A cross-section, not to scale. Under a slab building is soil, then gray clay and silt of the Beaumont Formation, 5 to more than 100 metres thick, with a lens of sand from an old stream channel. A dashed water table sits inside the clay. Below lie the Gulf Coast Aquifer's beds of sand, silt, clay and gravel; its fresh-water part averages about 1,000 feet thick. The layers keep going down, with no bedrock in reach. Soil Clay & silt · Beaumont Formation 5 m to 100+ m thick sand lens: an old stream channel water table Gulf Coast Aquifer beds of sand, silt, clay, gravel fresh-water part ≈ 1,000 ft (300 m) keeps going down not to scale
Rivers and the sea delivered the sediment in every layer. Only the soil on top formed in place, by weathering it.

Start here · The big picture

Zoom out: atoms build minerals, minerals build rocks, rocks build the ground

Four parts of Module 1, from smallest to largest Four panels joined by arrows. Atoms (Part 2, Matter Lab) join into minerals (Part 3, Mineral Bench), minerals join into rocks (Part 4, Rock Cycle Workshop), and rocks and sediment make the ground you map and measure (Part 1, Map Makers). Atoms Part 2Matter Lab Minerals Part 3Mineral Bench Rocks Part 4Rock Cycle Workshop The ground Part 1Map Makers nanometres (atoms) kilometres (the ground)

Four parts, one driving question.

Your team leads one part and teaches it. The class needs all four to explain the ground under campus.

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Part 1 · Map Makers lead this part

Reading the ground

  • Describe Earth as four connected systems.
  • Keep observations and inferences apart.
  • Find places, distances, and slopes on a map.
  • Explain what a satellite actually measures.
A topographic map of a hillFour closed contour lines nest around a hilltop marked with a small triangle. Dashed grid lines cross the map at 29.80° N latitude and 95.40° W longitude. 29.80° N 95.40° W

Part 1 · Key idea

Earth is four connected systems

The four spheres trade matter and energy Four circles: atmosphere at the top, hydrosphere on the right, geosphere at the bottom, biosphere on the left. Arrows run around the loop: air brings rain; rain soaks into the ground and swells clay; soil feeds plant roots; plants release water vapor back to the air. Atmosphere air Hydrosphere water, ice Geosphere rock, soil Biosphere living things rain soaks in, swells clay soil feeds roots plants give off water vapor EARTH SYSTEM

Matter and energy keep crossing between the four spheres.

So a change in one sphere always shows up in another. Ask which sphere your evidence belongs to.

Site SurveyA wet week (hydrosphere) swells the clay (geosphere), and foundation slabs crack.

Part 1 · Key idea

Observation or inference? Label every sentence

Observation · seen or measured

“The soil is gray, sticky when wet, and cracked after a dry week.”

Inference · concluded from evidence

“It is rich in clay that swells and shrinks with water.”

RuleStrong inferences rest on several observations. Label each sentence O or I.

Part 1 · Key idea

Latitude and longitude give an exact address

Latitude and longitude lines on a globe A globe with horizontal latitude lines at 0, 30 and 60 degrees north and south, and curved longitude lines from pole to pole. The equator is 0 degrees latitude. The prime meridian is 0 degrees longitude. Houston is marked at 29.8 degrees north, 95.4 degrees west. Houston 29.8° N, 95.4° W Equator 0° latitude Prime meridian 0° longitude North Pole · 90° N 30° N 30° S

Latitude: degrees north or south of the equator (0° to 90°).

Longitude: degrees east or west of the prime meridian (0° to 180°).

Use itWrite latitude first. One degree of latitude ≈ 111 km, so 0.01° ≈ 1.1 km.

Part 1 · Key idea

Map scale turns centimetres into metres

Measuring a distance with a map scale Points A and B sit 4 centimetres apart on a map. The scale bar shows 1 centimetre equals 50 metres, so the real distance is 4 times 50, which is 200 metres. A B 012345 cm 050100150200 m 1 cm = 50 m

A map scale says how much real ground each centimetre of map covers.

real distance = map distance × scale

Try itA to B is 4 cm. 4 cm × 50 m per cm = 200 m on the ground.

Part 1 · Key idea

Contour lines show height — and steepness

From a hill to its contour map Top: a side view of a hill 50 metres tall, steep on the left and gentle on the right, sliced at 10, 20, 30 and 40 metres. Bottom: the same slices seen from above as nested contour lines. On the steep left side the lines crowd together; on the gentle right side they spread far apart. 10 m20 m30 m40 m 50 m SIDE VIEW 10203040 VIEW FROM ABOVE steep: lines crowd gentle: lines spread out

A contour line joins points at the same height.

The contour interval is the height step between lines. Here it is 10 m.

Read itLines close together: steep. Far apart: gentle. The labels, not the spacing, tell you height.

Part 1 · Worked example · Map Makers' calculation

How steep is the ground between A and B?

Slope from a contour map Point A sits on the 100 metre contour and point B on the 150 metre contour, 4 centimetres apart on the map, with five contour intervals between them. Below, a right triangle shows a run of 200 metres and a rise of 50 metres, drawn to true proportion. 100110120130140150 m A B 4 cm on the map 1 cm = 50 m interval = 10 m run = 200 m rise = 50 m ≈ 14° true proportion
Map distance
4 cm
Scale
1 cm = 50 m
Contours crossed
5 intervals of 10 m
  1. Run (across)4 cm × 50 m/cm = 200 m
  2. Rise (up)5 × 10 m = 50 m
  3. Sloperise ÷ run = 50 m ÷ 200 m = 0.25
  4. Read it0.25 = a 25% grade: 25 m up for every 100 m across.
Answer

Slope = 0.25 (about 14°). Check: metres ÷ metres, so slope has no unit.

Part 1 · Key idea

Satellites measure reflected light, one pixel at a time

How a Landsat satellite senses the ground Sunlight shines down on the ground. Each surface reflects some light up to a Landsat satellite, which records it as a grid of pixels. One pixel covers 30 metres by 30 metres of ground. Landsat sunlight in reflected light out 1 pixel = 30 m × 30 m

Remote sensing is measuring Earth from far away, usually the sunlight it reflects.

Landsat 8 and 9 record 30 m pixels. Each passes over the same spot every 16 days; together, every 8.

Quick mathA campus 300 m wide is 300 ÷ 30 = 10 pixels across.

Part 1 · Worked example

Is that pixel grass or pavement? Use NDVI

Reflectance of grass and pavement A bar chart of example reflectance. Grass reflects 0.50 of near-infrared light and 0.08 of red light. A parking lot reflects 0.22 near-infrared and 0.20 red. Healthy plants reflect far more near-infrared than red. 00.20.40.6 fraction of light reflected 0.50 0.08 0.22 0.20 Grass Parking lot near-infrared (NIR) red light example pixel values

NDVI = (NIR − Red) ÷ (NIR + Red)

  1. Grass(0.50 − 0.08) ÷ (0.50 + 0.08) = 0.42 ÷ 0.58 = 0.72
  2. Parking lot(0.22 − 0.20) ÷ (0.22 + 0.20) = 0.02 ÷ 0.42 = 0.05
  3. Read it (NASA)0.6 to 0.8: dense, leafy plants. 0.1 and below: bare surfaces like rock or sand.
Answer

Grass ≈ 0.72, living plants. Lot ≈ 0.05, bare surface.

Part 1 · Common mistakes

Three map mistakes that cost points

Crowded contour lines are steep; spread lines are gentle steep gentle
✗ Mistake

“Lines far apart mean a tall hill.”

✓ Fix

Spacing shows steepness. Only the labels tell height.

Latitude is written first 29.8° N, 95.4° W
✗ Mistake

“Houston is at −95.4, 29.8.”

✓ Fix

Latitude first: 29.8° N, 95.4° W. Latitude never passes 90°.

Convert both distances to metres before dividing 5 lines ÷ 4 cm ✗ 50 m ÷ 200 m ✓
✗ Mistake

“Slope = 5 lines ÷ 4 cm.”

✓ Fix

Turn both into real metres first: rise in m ÷ run in m.

Part 1 · Check yourself

Your turn: find the slope from P to Q

Map for the slope question P sits on the 20 metre contour and Q on the 35 metre contour, 6 centimetres apart on the map. The scale is 1 centimetre equals 25 metres, and the contour interval is 5 metres. 20 m25 m30 m35 m P Q 6 cm on the map 02550 m 1 cm = 25 m · interval 5 m

P and Q are 6 cm apart and 3 contour intervals apart. What is the slope?

Show the answer

A, 0.10. Run = 6 cm × 25 m/cm = 150 m. Rise = 3 × 5 m = 15 m. Slope = 15 ÷ 150 = 0.10, a 10% grade. B divides intervals by centimetres; C uses 25 m as the run.

Part 2 · Matter Lab lead this part

Matter: what everything is made of

  • Name an element from its proton count.
  • Explain how ions and bonds form.
  • Explain why water dissolves so much.
  • Use phase changes and the energy they move.
  • Calculate mass percent in a formula.
A water moleculeA large oxygen atom, marked δ− (slightly negative), bonded to two smaller hydrogen atoms, each marked δ+ (slightly positive). O H H δ− δ+ δ+

Part 2 · Key idea

Count the protons and you know the element

An oxygen atom A simple model of an oxygen atom: a nucleus of 8 protons and 8 neutrons, with 2 electrons on an inner shell and 6 on an outer shell. A periodic-table tile reads 8, O, oxygen, 16.00. 8 O Oxygen 16.00 8 = atomic number = number of protons proton (+) neutron electron (−)
A teaching model: real electrons spread out in clouds, not neat circles.

An atom is the smallest piece of an element.

Its number of protons decides the element: 8 protons is always oxygen. Neutrons change the mass, not the element.

Census118 elements are known; about 90 occur in nature.

Open the Studio periodic table

Part 2 · Key idea

Ions: atoms that gained or lost electrons

Sodium gives an electron to chlorine A sodium atom with 1 outer electron passes it to a chlorine atom with 7 outer electrons. Sodium becomes a positive ion, Na plus. Chlorine becomes a negative ion, Cl minus. Opposite charges attract, forming the ionic bond in halite, rock salt. Na Cl 1 electron moves 11 protons, 1 outer electron 17 protons, 7 outer electrons Na⁺ Cl⁻ + − ionic bond = halite

An ion is an atom with an electric charge.

Lose electrons: positive ion. Gain electrons: negative ion.

Why it mattersOpposite charges attract. That pull, the ionic bond, holds halite (rock salt) together.

Part 2 · Key idea

How atoms hold on decides how a mineral behaves

Three kinds of chemical bond Ionic: positive and negative ions alternate in a grid, as in halite, which is brittle and splits into cubes. Covalent: silicon and oxygen atoms share electron pairs in a linked network, as in quartz, which is hard. Metallic: positive metal ions sit in a shared sea of electrons, as in native copper, which bends and conducts electricity. + − + − − + − + + − + − Ionic halite: brittle, splits into cubes SiO Covalent quartz: shared electrons, very hard +++++++++ Metallic copper: bends, carries current

Covalent sketch: a flattened picture of quartz's Si–O network (each Si really bonds to 4 O in 3-D).

Part 2 · Real data

Two elements make three-quarters of the crust

Elements in Earth's crust, percent by mass Bar chart. Oxygen 46.1 percent, silicon 28.2, aluminum 8.2, iron 5.6, calcium 4.2, sodium 2.4, magnesium 2.3, potassium 2.1, and every other element together about 0.9 percent. Oxygen 46.1% Silicon 28.2% Aluminum 8.2% Iron 5.6% Calcium 4.2% Sodium 2.4% Magnesium 2.3% Potassium 2.1% All others 0.9% ≈ 74%
Different studies estimate these within about 1 percentage point of each other.

Oxygen + silicon ≈ 74% of the crust's mass.

That is why most crustal minerals are silicates: minerals built from silicon and oxygen.

Mineral BenchCompare: silicon is 46.7% of pure quartz but 28.2% of the crust.

Part 2 · Key idea

Water is polar, so it pulls crystals apart

Water molecules surround dissolved ions A sodium ion, Na plus, is surrounded by water molecules turned with their negative oxygen ends toward it. A chloride ion, Cl minus, is surrounded by water molecules turned with their positive hydrogen ends toward it. Na⁺ Cl⁻ O ends (−) face Na⁺ H ends (+) face Cl⁻ oxygen (δ−) hydrogen (δ+)

Oxygen pulls shared electrons harder than hydrogen does. So water has a slightly negative end and slightly positive ends: it is polar.

ResultThose charged ends tug ions out of a crystal. Water dissolves salt; nothing melts.

Part 2 · Key idea · Matter Lab's build

Separate a mixture without breaking a single bond

A two-stage water-cleaning station Stage 1: muddy water pours through a funnel layered with gravel, sand, charcoal and cotton; particles stay behind and clearer water drips out. Stage 2: a solar still. Sunlight warms salty water in a bowl; water evaporates, condenses on plastic wrap, and drips into a cup in the middle. The salt stays in the bowl. gravelsandcharcoalcotton muddy, salty water Stage 1: filter traps particles by size plastic wrap vapor rises cup Stage 2: solar still water evaporates, then condenses; the salt stays in the bowl

A mixture can be separated without breaking any bonds.

A filter sorts particles by size. A solar still uses a phase change: water evaporates, dissolved salt stays behind.

Matter Lab buildTest water before, after the filter, and after the still. Record mL, clarity, and pH.

Part 2 · Key idea

Phase changes move energy, not atoms

Solid, liquid and gas, and the energy of changing between them Three boxes of particles: a solid in a tight ordered grid, a liquid packed but jumbled, a gas spread far apart. Melting and evaporating, moving right, absorb energy. Freezing and condensing, moving left, release energy. The number of particles never changes. Solid Liquid Gas melting freezing evaporating condensing absorbs energy (melting, evaporating) releases energy (freezing, condensing) 20 particles in every box: atoms are conserved

A phase change rearranges particles. No atoms appear or disappear, so mass is conserved.

Energy ruleMelting and evaporating absorb energy. Freezing and condensing release it.

Part 2 · Worked example · Matter Lab

How much energy does your solar still use?

Energy per gram of water Bar chart of energy per gram of water. Warming 1 gram by 1 degree Celsius takes 4.18 joules. Melting 1 gram of ice takes about 335 joules. Evaporating 1 gram of water near room temperature takes about 2,430 joules, almost 600 times the warming value. warm 1 g by 1 °C melt 1 g of ice evaporate 1 g near room temp. 4.18 J ≈ 335 J ≈ 2,430 J bar length = energy (joules)
Water evaporated
m = 50 g
Latent heat
L ≈ 2,430 J/g
  1. FormulaQ = m × L
  2. SubstituteQ = 50 g × 2,430 J/g
  3. MultiplyQ = 121,500 J ≈ 122 kJ
  4. ReverseWhen the vapor condenses on the wrap, it releases the same 122 kJ.
Answer

About 122,000 J: enough to warm 1 kg of water by 29 °C.

Latent heat: energy a phase change absorbs or releases. Values: 580 cal/g to evaporate, 80 cal/g to melt (Scripps Institution of Oceanography); 1 cal = 4.184 J. Storm Room uses this: condensing vapor powers storms.

Part 2 · Worked example · Practice Gym skill

What percent of quartz is silicon?

Quartz, SiO2, split by mass One silicon atom with a mass of 28.09 and two oxygen atoms of 16.00 each. A bar split by mass: silicon 46.7 percent, oxygen 53.3 percent. Si O O 28.09 16.00 16.00 SiO₂ 60.09 g/mol Si 46.7% O 53.3% share of the mass, not of the atoms
Formula
SiO₂ (quartz)
Atomic masses
Si = 28.09, O = 16.00
  1. Formula mass28.09 + 2 × 16.00 = 60.09
  2. Silicon28.09 ÷ 60.09 × 100 = 46.7%
  3. Oxygen2 × 16.00 = 32.00; 32.00 ÷ 60.09 × 100 = 53.3%
  4. Check46.7% + 53.3% = 100.0%
Answer

Quartz is 46.7% silicon and 53.3% oxygen by mass.

Part 2 · Common mistakes

Three matter mistakes to avoid

Same nine particles before and after melting →
✗ Mistake

“Melting turns the rock into new atoms.”

✓ Fix

Same atoms, new arrangement. Mass is conserved.

Salt dissolving: ions spread into the water
✗ Mistake

“The salt melted in the water.”

✓ Fix

It dissolved: water pulled its ions apart. Halite melts only at 801 °C.

Count the subscript SiO2 2 oxygens = 32.00
✗ Mistake

“%O in SiO₂ = 16.00 ÷ 60.09.”

✓ Fix

Count every atom: 2 × 16.00 = 32.00, so 53.3%.

Part 2 · Check yourself

Two quick checks

In the solar still, why is the water in the cup less salty than the water in the bowl?

Show the answer

B. Evaporation is a phase change of water alone. Dissolved ions do not evaporate at these temperatures, so the vapor that condenses and drips into the cup leaves them behind.

What percent of water, H₂O, is hydrogen by mass? (H = 1.008, O = 16.00)

Show the answer

B, 11.2%. Formula mass = 2 × 1.008 + 16.00 = 18.016. Hydrogen = 2.016 ÷ 18.016 × 100 = 11.2%. A forgets the 2; C and D count atoms instead of mass.

Part 3 · Mineral Bench lead this part

Minerals: prove what you are holding

  • Decide whether something is a mineral.
  • Explain how a crystal lattice shapes properties.
  • Identify minerals with streak, hardness, and density.
  • Report a density with an honest uncertainty.
A quartz crystalA large and a small quartz crystal, each a six-sided prism ending in a pointed tip, with small sparkles for their glassy shine.

Part 3 · Key idea

A mineral passes all five tests

One failed test is enough to rule something out.
TestQuartzGlacier iceObsidianCoal
Natural✓✓✓✓
Inorganic✓✓✓✗
Solid✓✓✓✓
Definite chemistry✓ SiO₂✓ H₂O✗ varies✗ varies
Orderly crystal✓✓✗ glass✗
VerdictMineralMineralNot a mineralNot a mineral

A mineral is naturally formed, inorganic (not made by living things), solid, has a definite chemical makeup, and has an orderly crystal structure.

SurpriseIce in a glacier is a mineral. An ice cube from your freezer is not: people made it.

“Definite” allows families such as feldspar to vary within set limits. Obsidian is volcanic glass, called a mineraloid.

Part 3 · Key idea

A hidden pattern sets the outside shape

Halite's cubic lattice and a halite crystal Left: sodium and chloride ions alternate in a repeating cube-shaped pattern. Right: a halite crystal shaped like a cube. The outside shape mirrors the inside pattern. inside: ions repeat in a cube pattern outside: a cube Na⁺ Cl⁻

Inside every mineral, atoms repeat in a 3-D pattern: its crystal lattice.

Halite's lattice is cubic, so salt grains are tiny cubes and break into cubes.

Mineral Bench buildGrow salt or alum crystals. The shape you see is the lattice showing through.

Part 3 · Key idea

One building block, five ways to connect it

The silica tetrahedron and the silicate families One silicon atom sits inside four oxygen atoms, forming a tetrahedron. Tetrahedra that share no corners make olivine. Sharing 2 corners makes single chains such as pyroxene. Sharing 2 or 3 makes double chains such as amphibole. Sharing 3 makes sheets such as mica. Sharing all 4 makes frameworks such as quartz and feldspar. SiO₄ tetrahedron 1 silicon + 4 oxygen Isolated olivine shares 0 Single chain pyroxene shares 2 Double chain amphibole shares 2–3 Sheet mica shares 3 Framework quartz, feldspar shares all 4 each triangle is one tetrahedron seen from above · "shares" = corners shared with neighbours
Why it matters: sheets let mica peel into flakes. Quartz is a framework with no weak plane, so it fractures instead of splitting.

Part 3 · Key idea

Identify with tests, not looks

Luster

Metallic, glassy, or dull shine.

Streak

Powder color on a tile.

Hardness

Scratch test, Mohs 1 to 10.

Cleavage or fracture

Flat or uneven breaks.

Density

Mass ÷ volume.

Special tests

Magnet, acid fizz. Never taste.

Mineral Bench buildYour key uses streak, hardness, magnet, fizz, and density.

Part 3 · Key idea

Color can lie. Streak tells the truth

Three hematite samples, one streak color Three pieces of hematite: one black and metallic, one steel gray, one red. Rubbed on an unglazed white tile, all three leave the same red-brown streak. A brassy pyrite sample leaves a dark greenish-black streak. black gray red brassy gold hematite ×3 pyrite same red-brown streak dark streak unglazed porcelain tile (streak plate)

Impurities and weathering change a mineral's color. Its streak, the color of its powder, stays the same.

Fool's goldPyrite looks like gold but leaves a dark streak. Real gold's streak is yellow.

Part 3 · Key idea · Mineral Bench data

Hardness: who scratches whom

The Mohs hardness scale with everyday test tools A ladder from 1 to 10: talc, gypsum, calcite, fluorite, apatite, feldspar, quartz, topaz, corundum, diamond. Test tools sit beside it at about: fingernail 2.5, copper coin 3, glass 5.5, steel nail 5.5, streak plate 6.5. The rungs are evenly spaced, but real hardness is not: diamond is about four times harder than corundum. 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond fingernail ≈ 2.5 copper coin ≈ 3 glass, steel nail ≈ 5.5 streak plate ≈ 6.5 real hardness: corundum ≈ ×4
Tool values are approximate; test on a fresh, clean surface.

Hardness is resistance to scratching. A harder mineral scratches a softer one.

CarefulMohs is an order, not a measurement. Diamond (10) is about 4 times harder than corundum (9).

Part 3 · Key idea

Density: how much mass in each cubic centimetre

Measuring volume by water displacement A balance reads 132.6 grams for a rock. A graduated cylinder holds water at 20.0 millilitres. With the rock inside, the water rises to 70.0 millilitres. The rock's volume is the rise: 50.0 millilitres, which equals 50.0 cubic centimetres. 0 20 40 60 80 100 20.0 mL 0 20 40 60 80 100 70.0 mL before after rise = 50.0 mL 132.6 g balance

density = mass ÷ volume  ·  d = m ÷ V

For an odd-shaped rock, find volume by displacement: how far it raises the water.

Units1 mL = 1 cm³, so density comes out in g/cm³.

Part 3 · Worked example · Practice Gym skill

Which mineral is Sample A?

Reference densities on a number line Six reference minerals on a density line in grams per cubic centimetre: halite 2.17, quartz 2.65, fluorite 3.18, corundum 4.02, pyrite 5.02, galena 7.58. Each has a plus or minus 5 percent window; the windows never overlap. Sample A, at 2.65, falls only in the quartz window. 2 3 4 5 6 7 8 g/cm³ halite 2.17 quartz 2.65 fluorite 3.18 corundum 4.02 pyrite 5.02 galena 7.58 Sample A: 2.65 shaded = ±5% window around each value
Neighbouring values are at least 20% apart, so a careful measurement matches only one mineral.
Mass
132.6 g
Water level
20.0 mL → 70.0 mL
  1. Volume70.0 − 20.0 = 50.0 mL = 50.0 cm³
  2. Densityd = 132.6 g ÷ 50.0 cm³ = 2.65 g/cm³
  3. MatchOnly quartz (2.65) is within 5%.
  4. Check2.65 × 50.0 = 132.5 g ≈ 132.6 g ✓
Answer

Sample A is quartz, 2.65 g/cm³.

Part 3 · Worked example · Site Survey rubric

How sure is your density? Report ±

Sample A's density with its uncertainty A zoomed number line from 2.40 to 2.90 grams per cubic centimetre. Sample A is plotted at 2.65 with an error bar from 2.60 to 2.70. Quartz, at 2.65, sits inside the bar. Halite at 2.17 and fluorite at 3.18 are far off the line. 2.40 2.50 2.60 2.70 2.80 2.90 Sample A: 2.65 ± 0.05 quartz 2.65 ← halite 2.17 is off this scale fluorite 3.18 is off this scale →
  1. Each readingThe cylinder reads to ±0.5 mL.
  2. VolumeTwo readings: 50.0 ± 1.0 mL. That is 1.0 ÷ 50.0 = 2%.
  3. Mass±0.1 g of 132.6 g is under 0.1%: too small to matter.
  4. Density2% of 2.65 ≈ 0.05, so d = 2.65 ± 0.05 g/cm³.
Answer

2.65 ± 0.05 g/cm³: from 2.60 to 2.70. Only quartz fits.

The biggest source of uncertainty sets your ±. Here it is the cylinder, not the balance.

Part 3 · Common mistakes

Three mineral mistakes to avoid

A gold-colored sample with a dark streak
✗ Mistake

“It's gold-colored, so it's gold.”

✓ Fix

Run streak and hardness. Pyrite's streak is dark; gold's is yellow.

Mohs steps are not equal 1, 2, 3… 9 vs 10
✗ Mistake

“Quartz (7) is 7 times harder than talc (1).”

✓ Fix

Mohs only puts minerals in order. The steps are uneven.

Volume is the rise in water level V = 70.0 mL ✗ V = 70.0 − 20.0 ✓
✗ Mistake

“The volume is the final water level.”

✓ Fix

Volume is the rise: final level − starting level.

Part 3 · Check yourself

Two quick checks

Sample B: mass 227.4 g; water rises from 15.0 mL to 45.0 mL. Which mineral? (halite 2.17, quartz 2.65, fluorite 3.18, corundum 4.02, pyrite 5.02, galena 7.58)

Show the answer

B, galena. V = 45.0 − 15.0 = 30.0 cm³. d = 227.4 ÷ 30.0 = 7.58 g/cm³. Using 45.0 mL as the volume gives 5.05 and the wrong answer, pyrite.

Which one is a mineral?

Show the answer

C. Glacier ice is natural, inorganic, solid, H₂O, and crystalline. Obsidian has no crystal structure, coal comes from plants, and a lab-grown sapphire was made by people.

Part 4 · Rock Cycle Workshop lead this part

Rocks: every one keeps a record

  • Sort rocks by how they formed.
  • Read crystal size as a cooling clock.
  • Calculate pressure at depth.
  • Read a P–T point and trace paths through the rock cycle.
Granite, sandstone and gneiss texturesThree rock samples side by side: granite with large interlocking crystals, sandstone made of rounded grains, and gneiss with its minerals lined up in bands. granite sandstone gneiss

Part 4 · Key idea

Three families, named for how they formed

Igneous, sedimentary and metamorphic rock Igneous rock such as granite shows interlocking crystals that grew as melt cooled. Sedimentary rock such as sandstone shows rounded grains laid down in layers, then pressed and cemented. Metamorphic rock such as gneiss shows minerals lined up in bands after heat and pressure changed the rock without melting it. Igneous cooled from melted rock granite, basalt, obsidian Sedimentary laid down, pressed, cemented sandstone, shale, limestone Metamorphic changed by heat and pressure slate, schist, gneiss clue: interlocking crystals clue: grains in layers, fossils clue: lined-up bands
Read texture first: grain size, layers, and lined-up bands each tell you where a rock formed.

Part 4 · Key idea · Practice Gym rule card

Crystal size is a cooling clock

Cooling time sets igneous texture A cooling-time scale from 1 hour to 100,000 years, each mark ten times the last. Under 1 day: glassy, like obsidian. From 1 day to 1,000 years: aphanitic, fine crystals too small to see, like basalt. Over 1,000 years: phaneritic, large interlocking crystals, like granite. Slow cooling first and then fast cooling gives porphyritic: big crystals in a fine background. 1 hour 1 day 1 year 1,000 y 100,000 y cooling time · each step on this scale is much longer than the last glassy aphanitic (fine) phaneritic obsidian basalt granite porphyritic: slow, then fast big crystals in a fine background
Classroom rule card used by the Forge and the Practice Gym. In nature, glass also needs thick, silica-rich lava.

Slow cooling gives atoms time to join big crystals. Fast cooling freezes them small, or as glass.

Rock Cycle Workshop buildCool one cup of salt or alum solution fast and one slowly. Measure crystal size in mm.

Part 4 · Key idea

Sedimentary rock: break it, move it, drop it, glue it

From mountain to sedimentary rock in five steps Six panels. 1, weathering breaks rock apart. 2, erosion: water carries the grains away. 3, deposition: grains settle in layers, biggest at the bottom. 4, compaction: the weight of new layers squeezes old ones. 5, cementation: minerals from water glue the grains together. The result is sedimentary rock such as sandstone or shale. 1 Weathering rock breaks apart 2 Erosion water carries grains 3 Deposition grains settle in layers 4 Compaction weight squeezes layers 5 Cementation minerals glue grains = Sedimentary rock sandstone, shale

Weathering, erosion, deposition, compaction, cementation. The last two together are lithification: loose sediment becoming rock.

Site SurveyHouston's clay was delivered and dropped by rivers but never lithified. USGS maps it as unconsolidated: still loose.

Part 4 · Key idea

Metamorphic rock: changed, never melted

Pressure lines up flat minerals Before: flat mica flakes point in every direction. After squeezing from above and below: the flakes line up in parallel bands, called foliation. Below: with more heat and pressure, shale becomes slate, then schist, then gneiss. before: flakes point every way after: lined up = foliation squeeze shale slate schist gneiss more heat and pressure →

Heat and pressure rebuild solid rock into new minerals. Squeezing lines flat minerals up into bands: foliation.

Texas evidenceLlano's Valley Spring Gneiss and Packsaddle Schist were metamorphosed about 1,050 million years ago.

Part 4 · Worked example · Rock Cycle Workshop's calculation

How much pressure 10 km down?

Pressure grows steadily with depth A straight-line graph of pressure against depth for rock of density 2,800 kilograms per cubic metre. At 5 kilometres pressure is 137 megapascals; at 10 kilometres, 274; at 20, 549; at 30, 823. That is about 27.4 megapascals for every kilometre. 0 5 10 15 20 25 30 0 300 600 900 depth (km) pressure (MPa) 137 274 549 823 ρ = 2,800 kg/m³
Density ρ
2,800 kg/m³
Gravity g
9.8 m/s²
Depth h
10 km
  1. Metres firsth = 10 km = 10,000 m
  2. MultiplyP = ρgh = 2,800 × 9.8 × 10,000 = 274,400,000 Pa
  3. Megapascals274,400,000 ÷ 1,000,000 ≈ 274 MPa
  4. Kilobars274 MPa ÷ 100 = 2.74 kbar
Answer

≈ 274 MPa = 2.74 kbar. Check: 27.4 MPa per km × 10 km ✓

Part 4 · Worked example · Practice Gym skill

Read a P–T point: solid, metamorphic, or melting?

The Practice Gym's P–T map Temperature from 0 to 1,300 degrees Celsius runs across; pressure from 0 to 10 kilobars runs down. Below 200 degrees the rock is unchanged. From 200 to 450 is low-grade metamorphic, 450 to 700 medium-grade, 700 and up high-grade. The solidus line, T equals 650 plus 25 times P, runs from 650 degrees at the surface to 900 degrees at 10 kilobars. Right of it, melting has begun. Point A at 6 kilobars and 700 degrees is high-grade metamorphic. Point B at 2 kilobars and 760 degrees is past the solidus. 0 200 450 700 1000 1300 0 2 4 6 8 10 temperature (°C) pressure (kbar) · deeper ↓ unchanged low medium high melting has begun solidus A B

Practice Gym solidus: Ts = 650 + 25P

  1. Point A · solidusP = 6 kbar: Ts = 650 + 25 × 6 = 800 °C
  2. Compare700 °C is not above 800 °C, so no melting.
  3. Grade700 °C is in the 700 °C-and-up band: high grade.
Answer

A is high-grade metamorphic. B (760 °C at 2 kbar, Ts = 700) has started to melt.

Model checkThe Forge uses its own curves (dry granite: about 1,019 °C at 6 kbar; wet: about 651 °C). Use your model's curve.

Both are simplified classroom models, not universal rock limits. Past the solidus, melting has begun: part solid, part melt. A fully liquid rock needs the higher liquidus.

Part 4 · Key idea · Practice Gym skill

The rock cycle is a network with shortcuts

Rock-cycle network Five states joined by processes. Magma cools and crystallizes into igneous rock. Igneous rock can melt, be metamorphosed, or weather and erode into sediment. Sediment is buried and lithified into sedimentary rock. Sedimentary rock can be uplifted and weathered back into sediment, metamorphosed, or melted. Metamorphic rock can melt or be uplifted and weathered into sediment. Red arrows run on Earth's internal heat; blue arrows run on the Sun and gravity. cool melt heat + pressure weather, erode bury, lithify uplift, weather heat + pressure melt melt uplift, weather Magma Igneous rock Metamorphic rock Sediment Sedimentary rock internal heat Sun + gravity

Any rock can become any other. There is no fixed order and no required “next” step.

Shortest pathMetamorphic → sedimentary: uplift and weather (→ sediment), then bury and lithify. 2 steps.

Two engines: Earth's internal heat (red) and the Sun plus gravity (blue).

Part 4 · Common mistakes

Three rock mistakes to avoid

Metamorphism happens below the melting line solidus metamorphic: still solid
✗ Mistake

“Metamorphic rock melted and hardened again.”

✓ Fix

It never melted. Melted rock that cools is igneous.

Time, not temperature, sets crystal size time sets crystal size
✗ Mistake

“Big crystals mean hotter magma.”

✓ Fix

Cooling time sets size. Same melt, slow cooling: big crystals.

Partial melt: crystals in liquid
✗ Mistake

“Past the solidus, the rock is all liquid.”

✓ Fix

Melting has only begun: crystals sit in melt.

Part 4 · Check yourself

Two quick checks

What is the fewest number of processes that turns magma into sedimentary rock?

Show the answer

C, 3. Cool and crystallize (→ igneous), weather and erode (→ sediment), bury and lithify (→ sedimentary). Magma cannot skip straight to sediment.

Practice Gym model: a rock sits at 4 kbar and 500 °C. What state is it in?

Show the answer

C. Ts = 650 + 25 × 4 = 750 °C, and 500 °C is below it, so the rock is solid. 500 °C sits in the 450–700 °C band: medium grade.

Part 5 · Every team · Site Survey

Use it in your project

“What is the ground under this campus actually made of, and what had to happen for it to end up here?”

  • Draw a site profile with evidence for every layer.
  • Defend your claim with three lines of evidence.
  • Fill the bench table with units and ±.
  • Find the slides your team's build needs.
Open the Site Survey project Project Library
The four Site Survey deliverablesFour cards: a site profile with ground layers and a dashed water table, a claim whose lines are marked O for observation or I for inference, an empty bench table, and a field journal. site profile claim + evidence OIO bench table field journal

Use it · Site Survey · Site profile cross-section

Every layer needs a material, a thickness, and a reason

How to label one layer of your site profile A cross-section from the ground surface down to the water table. Each layer carries a label card with three parts: material, thickness with units, and the evidence that put it there, marked O for observation or D for data. The water table depth comes from the nearest state well, with its date. surface water table MATERIAL gray clay and silt THICKNESS your estimate, in m (± range) EVIDENCE (O) sample · (D) USGS unit depth from nearest TWDB well plus the date it was measured Label the scale, or write “not to scale.”
Turn in
Site profile cross-section · Studio Upload, up to 3 image pages
Do
Surface down to the water table. Each layer: material, thickness with units, and the observation or data behind it.
Data
USGS state geologic maps · TWDB well viewer · USDA Web Soil Survey
Slides
Ground layers · Sediment · O vs I

Use it · Site Survey · Ground-origin claim and defense

One claim, three independent lines of evidence

A claim held up by three lines of evidence A claim sits on top of three pillars. Pillar 1 is data: what the USGS map unit says about your site. Pillar 2 is observation: your own sample's grain size, color, and behavior when wet. Pillar 3 is a test: your bench results. Each sentence is labeled O for observation or I for inference. Reasoning connects the pillars to the claim. CLAIM what the ground is made of and how it got here REASONING: why each line of evidence supports the claim 1 · Data2 · Observation3 · Test what the USGSmap unit saysabout your site your sample'sgrain size, color,and feel when wet your benchdensity, hardness,and fizz results O / I O / I O / I independent = each comes from a different source
Turn in
Ground-origin claim and defense · Assessment Center, typed, 400–600 words
Do
Label every sentence O (observation) or I (inference). Never let an inference pass as an observation.
Start with
“We observed ___. From that we infer ___.”
Slides
O vs I · How sediment becomes rock

Use it · Site Survey · Bench identification table

Fill the bench table like a scientist

One worked row (Sample A from the density slides). Your table has six samples.
SampleMass (g)Volume (cm³)Density (g/cm³)HardnessStreakTexture / breakIdentificationConfidence
A132.6 ± 0.150.0 ± 1.02.65 ± 0.05≈ 7: scratches glasswhiteglassy; curved fracturequartzhigh: density and hardness agree
Units

Every number carries a unit and a ±.

Decider

Name the property that settled the ID.

Revise

Changed an ID? Your journal names the evidence.

Use it · Site Survey · Your team's build

The slides your build and teach-back need

Map Makers · landform in a box

Even contours, a grid, a scale bar, a slope.

Matter Lab · water-cleaning station

Filter separates; still changes phase. Measure both.

Mineral Bench · ID station and key

Five tests, a yes/no key, quartz near 2.65.

Rock Cycle Workshop · demo bench

Cooling rate, graded layers, lined-up flakes.

Rock Cycle ForgeForge readouts are model evidence: “When we changed ___, the ___ changed.” Open the Forge

Use it · The rest of the year

Module 1 comes back in every project

Part 6 · Reference · Formula sheet

Every Module 1 formula on one page

Density

d = m ÷ V

V = level after − level before. 1 mL = 1 cm³. Example

Uncertainty

± from your worst reading

Add reading errors; turn into %; apply that % to the answer. Example

Mass percent

% = n × atomic mass ÷ formula mass × 100

Count every atom (subscripts). Example

Pressure at depth

P = ρ g h

g = 9.8 m/s². 1 MPa = 1,000,000 Pa. 100 MPa = 1 kbar. ≈ 27.4 MPa per km at 2,800 kg/m³. Example

Maps

real = map × scale · slope = rise ÷ run

Both in metres. % grade = slope × 100. 1° latitude ≈ 111 km. Example

NDVI

(NIR − Red) ÷ (NIR + Red)

−1 to +1. 0.6–0.8 dense plants; 0.1 or less bare ground. Example

Latent heat

Q = m × L

Evaporate ≈ 2,430 J/g; melt ≈ 335 J/g; warm water 4.18 J/g per °C. Example

P–T state (Practice Gym)

Ts = 650 + 25P

T > Ts: melting begun (Gym answer “Molten”). Else ≥700 high, 450–700 medium, 200–450 low, <200 unchanged (°C). Example

Texture rule card

time sets crystal size

>1,000 y phaneritic · 1 day–1,000 y aphanitic · <1 day glassy · slow then fast porphyritic. Slide

Reference densities (g/cm³)

halite 2.17 · quartz 2.65 · fluorite 3.18 · corundum 4.02 · pyrite 5.02 · galena 7.58

Mohs scale

1 talc · 2 gypsum · 3 calcite · 4 fluorite · 5 apatite · 6 feldspar · 7 quartz · 8 topaz · 9 corundum · 10 diamond. Fingernail ≈ 2.5, coin ≈ 3, glass ≈ 5.5, streak plate ≈ 6.5.

Rock-cycle moves

melt · cool and crystallize · weather and erode · bury and lithify · heat and pressure · uplift. Network

Part 6 · Reference · Vocabulary

Module 1 words, in plain language

Geosphere
Earth's rock, soil, and interior.
Hydrosphere
All of Earth's water, including ice.
Atmosphere
The layer of air around Earth.
Biosphere
All living things.
Observation
What you see, touch, or measure.
Inference
A conclusion drawn from observations.
Latitude
Degrees north or south of the equator.
Longitude
Degrees east or west of the prime meridian.
Map scale
How much real distance a map distance stands for.
Contour line
A map line joining points of equal height.
Contour interval
The height step between contour lines.
Remote sensing
Measuring Earth from far away, often by satellite.
Pixel
One square of a satellite image (30 m for Landsat).
Atom
The smallest piece of an element.
Element
A substance defined by its number of protons.
Ion
An atom that gained or lost electrons, so it has a charge.
Ionic bond
Attraction between oppositely charged ions.
Covalent bond
Atoms sharing pairs of electrons.
Polar
Having a slightly negative end and a slightly positive end.
Mixture
Substances combined without bonding; separable physically.
Phase change
A change of state, such as melting or evaporating.
Latent heat
Energy a phase change absorbs or releases.
Mineral
Natural, inorganic, solid, definite chemistry, orderly crystal.
Crystal lattice
The repeating 3-D pattern of atoms in a mineral.
Silicate
A mineral built from silicon–oxygen tetrahedra.
Luster
How a mineral's surface reflects light.
Streak
The color of a mineral's powder.
Hardness
Resistance to scratching (Mohs scale).
Cleavage
Breaking along flat planes.
Fracture
Breaking unevenly or in curves.
Density
Mass per unit volume.
Igneous rock
Rock that cooled from melt.
Sedimentary rock
Rock made of deposited, compacted, cemented sediment.
Metamorphic rock
Rock changed by heat and pressure without melting.
Lithification
Compaction plus cementation: sediment becoming rock.
Foliation
Minerals lined up in bands by pressure.
Solidus
The temperature where melting begins.
Phaneritic
Crystals big enough to see: slow cooling.
Aphanitic
Crystals too small to see: fast cooling.
Porphyritic
Big crystals in a fine background: slow, then fast.
Rock cycle
The network of paths that turn any rock into any other.
Unconsolidated
Loose sediment that has not become rock.

More wordsLook up any term in the Ascent Lexicon.

Part 6 · Reference · Trustworthy data

Real data for your project, from the people who measure it

Cite itWrite the source, the link, and the date you read it. Live data changes.

Part 6 · Ready for your project?

Three last checks

Which sentence is an inference?

Show the answer

C. No one watched it happen; it is concluded from evidence such as fine, layered grains and the USGS map unit. A, B, and D are seen or measured.

A rock has large, interlocking crystals you can see. How did it most likely cool?

Show the answer

A. Visible interlocking crystals (phaneritic) mean slow cooling, over 1,000 years on the rule card, like granite.

Your bench density is 4.0 ± 0.1 g/cm³. Which mineral fits?

Show the answer

B. 4.0 ± 0.1 covers 3.9 to 4.1, and only corundum's 4.02 is inside that range.

You made it through Module 1

Now go read your own ground

Practice the math, test ideas in the Forge, then build.

Site Survey project Practice Gym · Module 1 Rock Cycle Forge Module 1 page
A hand lens over layered groundA hand lens magnifies sand grains held above three layers of ground under a green surface line.