If you’ve ever seen a picture (or model) of a granite outcrop covered in long, sharp cracks, you might have bumped into this classic Earth
If you’ve ever seen a picture (or model) of a granite outcrop covered in long, sharp cracks, you might have bumped into this classic Earth science question:
“What type of weathering is illustrated by the cracks in the simulated granite outcrop below?”
The short answer is:
✅ Mechanical (physical) weathering – most commonly frost wedging and pressure-release jointing.
In simple terms, solid granite stone gradually cracks apart due to physical forces like freezing water and the release of deep underground pressure. Over time, those forces carve visible fractures into massive granite outcrops.
In this guide, we’ll unpack:
- How granite geology and composition set it up for cracking
- What mechanical weathering is, and how frost wedging and unloading work
- How those same properties affect granite countertops in your home
- Where granite sits in natural stone comparisons (vs quartz, marble, soapstone, concrete)
- How Aardwolf granite products fit into both the geology and the design story
Understanding Granite Stone Before We Talk Weathering
To understand why granite cracks, we need to know what it is.
Granite geology and composition
Granite is an intrusive igneous rock formed when molten magma cools slowly deep under the Earth’s surface. This slow cooling allows large crystals to grow, typically:
- Quartz – very hard and glassy
- Feldspar – white, cream, or pink minerals
- Mica and accessory minerals – dark or silvery flakes
These minerals create the core characteristics of granite:
- High hardness and scratch resistance
- Excellent heat resistance
- Slight natural porosity
- Ability to take a beautiful polish in slabs and tiles
If you want to see granite’s story from magma to countertop, these are great reads:
Those articles explain how granite stone starts far underground long before it becomes a building material.
What Type of Weathering Causes Cracks in Granite Outcrops?
When you see a simulated granite outcrop covered in fractures, the question is asking:
Is this chemical weathering, biological weathering, or mechanical (physical) weathering?
The correct umbrella answer: mechanical (physical) weathering
The cracks in a granite outcrop are usually illustrating mechanical weathering – the breakdown of rock into smaller pieces without changing its chemical composition.
For granite, the two key mechanical processes are:
- Frost wedging (freeze–thaw weathering)
- Pressure-release (unloading) and exfoliation jointing
Let’s break each one down.
Frost Wedging: Water in Cracks That Acts Like a Wedge
One of the most common answers for the textbook-style question is frost wedging, a type of mechanical weathering.
How frost wedging breaks granite
- Water enters small cracks in the granite outcrop.
- When temperatures drop below freezing, the water turns to ice.
- Ice expands (about 9% more volume than water).
- That expansion exerts pressure on the crack walls.
- Repeated freeze–thaw cycles gradually widen and deepen the cracks.
Over many years, this repeated wedging can:
- Turn hairline fractures into visible cracks
- Break off blocks of granite along joint lines
- Create the fractured look you see in simulated granite outcrops
Because the chemical composition of granite doesn’t change—only its shape and size—this is 100% mechanical weathering.
Pressure-Release Jointing: Granite Expands and Cracks as Pressure Drops
Another key type of weathering often illustrated with granite outcrops is pressure-release jointing (also called unloading).
How unloading works in granite stone
When granite first forms, it’s buried under kilometers of rock, under enormous pressure.
Later:
- Plate tectonics uplift the crust.
- Erosion slowly removes overlying layers.
- Pressure on the granite decreases (unloads).
- The granite slightly expands, especially toward the surface.
- This expansion causes cracks parallel to the surface—called sheet joints or exfoliation joints.
These joints can then be further widened by frost wedging, root growth, or other mechanical processes.
To see the bigger geologic story, check out:
- What geologic process can change granite into gneiss?
- How can a large block of granite form layers like an onion?
Those pieces show how granite can evolve through metamorphism and exfoliation into banded or onion-like forms at the landscape scale.
Spheroidal (Onion-Skin) Weathering in Granite
When mechanical weathering continues along curved joints and edges, we get spheroidal weathering, often called onion-skin weathering.
- Corners and edges of blocks weather fastest.
- Blocks become rounded.
- Outer layers peel away in curved sheets, like layers of an onion.
This is especially noticeable in large granitic domes and boulders, where it looks like someone has peeled off thin shells of granite stone over time.
Does Chemical Weathering Play a Role in Granite Cracks?
While the exam question usually focuses on mechanical weathering, chemical weathering does play a supporting role. For example:
- Feldspar in granite can alter to clay minerals.
- Slight chemical changes can weaken the rock along grain boundaries.
However, the visible cracks drawn in a simulated granite outcrop are typically meant to illustrate physical processes like frost wedging and unloading—not chemical breakdown.
From Granite Outcrops to Granite Countertops: Why Weathering Matters
You’re probably not worried about your kitchen turning into a mountain range, but the same properties that make granite crack outdoors affect how it behaves as a countertop.
Is granite non-porous?
Granite is not perfectly non-porous. It has tiny spaces between mineral grains and along microcracks. In nature, those microspaces are where water and ice get in, driving weathering.
In your home, they’re why we:
- Recommend sealing granite
- Talk about stain prevention
- Emphasize proper cleaning practices
For a focused look at porosity and what it means practically, see:
Clean granite countertops and sealing
Because of its slight porosity:
- Unsealed granite can darken or stain if spills sit too long.
- A good penetrating sealer fills or lines those micro-pores.
- Sealing makes it easier to maintain clean granite countertops and avoid deep removing stains from granite later on.
Granite vs Other Countertop Materials: Durability and Weathering
Weathering in nature gives us clues about how granite compares to other materials in a natural stone countertop comparison.
Granite vs quartz countertops
- Granite – natural, slightly porous, requires sealing, excellent heat resistance, unique patterns.
- Quartz – engineered (resin-based), non-porous, doesn’t need sealing, less tolerant of high heat.
Granite vs marble: pros and cons
- Marble – softer, more porous, more prone to etching and chemical weathering (especially by acids).
- Granite – harder and more resistant to both mechanical and chemical weathering, better for heavy-use kitchens.
Granite vs soapstone durability
- Soapstone – very dense and stain-resistant but softer and easier to scratch.
- Granite – more scratch-resistant, better at holding a polished finish under everyday wear.
Granite better than concrete countertops?
- Concrete – highly porous, can crack and weather relatively quickly without meticulous sealing.
- Granite – naturally tough, less prone to cracking, easier to maintain long-term once sealed.
All the ways granite survives outcrops, domes, and cliffs make it a strong contender for countertop applications—especially when properly installed and maintained.
Cost, Sourcing, and Design: Bringing Geology into Your Kitchen
Granite countertop cost and where to buy
Granite countertop cost depends on:
- Color and pattern (rarer stones cost more)
- Slab thickness and finish
- Edge profiles and number of cutouts
- Local fabrication and installation costs
You can find:
- Affordable granite countertop options at big-box stores
- More unique colors and patterns from local fabricators
- Slab yards and wholesale granite suppliers where you can hand-pick your stone
Design choices: white, black, and everything in between
Granite’s weathering story is only half the fun—the rest is design.
- A white granite countertop can brighten a space and pair beautifully with dark cabinets.
- Black granite countertops add drama and luxury, especially with light or wood-tone cabinets.
Maximize the look with:
- Matching granite backsplash designs (full-height slabs look especially striking)
- Thoughtful pairing granite with cabinet colors for a cohesive design
Aardwolf Granite: Premium Slabs With a Deep Earth Story
If you want to bring this geologic history into a real home project, the Aardwolf granite countertop collection is a strong place to start.
- Aardwolf premium granite slabs are selected for strength, consistency, and attractive patterning.
- Many of the best Aardwolf granite colors work with both modern and classic interiors.
- With Aardwolf granite installation services, you get professional templating, cutting, edge finishing, and sealing for long-lasting performance.
- The Aardwolf granite pricing guide helps you compare options across budgets and styles, from practical to showpiece.
In other words: you’re taking rock that has survived millions of years of weathering and giving it a starring role in your kitchen or bath.
Final Answer: What Type of Weathering Do Those Granite Cracks Show?
So, back to the original question:
What type of weathering is illustrated by the cracks in the simulated granite outcrop below?
The correct conceptual answer is:
✅ Mechanical (physical) weathering – most often frost wedging and/or pressure-release jointing.
Those long, sharp cracks represent the physical breaking of granite stone without changing its chemical makeup. It’s the same tough, igneous rock—just fractured by natural forces over time.