Weathering: The Response of Rocks to a New Environment

By A. Orgonik

Caumsett State Park

How is this rock’s environment different from where it formed?

Boulders in the woods at Caumsett.

Let’s take a closer look at these rocks. What beautiful cranberry mineral is in this one?

What weathering processes might be going on in these rocks knowing (and seeing here!) the climate of Long Island?

Water in what state?

What is happening here?

What weathering process appears to be happening here?

Is it a physical or chemical process?

What weathering process is happening here?

A close-up view!Is this chemical or physical?What weathering

process is happening here? EXFOLIATION

PHYSICAL

MONTAUK POINT: Long Island, NY

What mineral is the cause of this beautiful purple/red sand?

Remember this one?

Where does sand come from? What processes formed the sand we see here?

Sand is the remains of weathered and eroded rock!

Welcome to Huntington Cemetery! Step inside to another real-life weathering laboratory!

Wow! We haven’t even stepped inside and we have evidence of weathering in the gate!

What process is this and is it physical or chemical?

We are going to look at cemetery rocks…(tombstones!) and observe the weathering that has occurred in them.

Since tombstones are dated we can even determine how long the weathering has occurred!

Here is a typical marble tombstone which used to be a very popular rock for cemeteries.

What mineral largely composes the rock marble?

What is the hardness of this mineral? Why was it a good rock for tombstones?

Here is another type of tombstone. It is made up of slate.

Compare the two tombstones in the next picture. How do they differ in terms of the types of weathering that has occurred to each?How do they compare in appearance? Which appears more weathered?

Marble Slate

Marble Slate

Which tombstone is older?

Marble Slate

This means that rocks can weather at different rates!

This is called “Differential Weathering”

Rocks weather at different rates due to differences in mineral composition.

Some minerals are more stable at the earth’s surface than others! These take longer to weather.

Calcite is very unstable at the earth’s surface in certain climate types. Which type in particular?

What weathering process causes the tombstones to “dissolve”? Is this chemical or physical?

CO2 CO2

But even slate tombstones are not immune to weathering!

What weathering process is occurring here? Is it physical or chemical?

More tombstones undergoing weathering! What process might be happening here, knowing the climate of Long Island?…

Another tombstone weathering (for almost 200 years!)Its distinct color indicates one weathering process going on! Which one?

What other process is occurring?

EXFOLIATION

Slatey cleavage seen due to weathering!

Why does the climate of Long Island contribute to exfoliation and frost action of these tombstones?

Living organisms can also weather rock!

Here are lichens, organisms that can make a living on bare rock (in this case a tombstone…)

Lichens secrete acids that dissolve rock!

REVIEW: What types of weathering processes can you see here?

EXFOLIATION

Another view of the previous tombstone

The climate of L.I. (its fluctuating temperatures) is even causing these tombstones to heave up out of the ground!

It’s time for us to leave, but weathering processes continue 24-7!

What will this place look like in another 50 years?