The Ripple Effect

How Water Physically Breaks Apart Rock

Mechanical weathering is the physical breakdown of rock into smaller fragments without altering the rock's chemical composition. Water is the dominant agent of mechanical weathering across New York State, operating through several key processes.

Frost Wedging (Ice Wedging)

As discussed in Part 1, water that enters cracks in rock and freezes can exert enormous pressure. In New York State, the climate creates ideal conditions for frost wedging — the average number of freeze-thaw cycles per year ranges from 60 to over 100 depending on the region. The Catskill Mountains, Adirondacks, and Hudson Highlands all show extensive evidence of frost wedging in exposed rock faces.

Stream Erosion, Transportation, and Deposition

Running water is the most significant agent of erosion in New York State. When water flows over land, it picks up and transports sediment. The ability of a stream to erode and transport sediment depends on several factors:

Abrasion

Abrasion occurs when transported sediment scrapes and grinds against rock surfaces and other sediment particles. This process smooths and rounds rock fragments during transport. The degree of rounding increases with transportation distance — angular fragments near a source become rounded cobbles and pebbles downstream.

The ESRT and Particle Size

The Earth Science Reference Tables (ESRT) include a chart showing the relationship between stream velocity and the particle sizes that can be transported. As stream velocity increases, progressively larger particles can be carried. Clay requires the least velocity to remain in transport, while boulders require the greatest velocity. This relationship is essential for interpreting depositional environments.

When Water Changes Rock at the Molecular Level

Unlike mechanical weathering, which breaks rock into smaller pieces without changing its composition, chemical weathering alters the actual mineral composition of rock. Water is the essential ingredient in nearly all chemical weathering reactions. In New York State, chemical weathering works alongside mechanical weathering to shape the landscape.

Dissolution

Dissolution occurs when water dissolves soluble minerals. Because water is polar, it is an excellent solvent — particularly for ionic compounds. The most dramatic examples in New York State involve limestone (calcium carbonate, CaCO₃). When water absorbs carbon dioxide (CO₂) from the atmosphere or soil, it forms a weak carbonic acid (H₂CO₃) that readily dissolves limestone:

Oxidation

Oxidation occurs when oxygen dissolved in water reacts with minerals — especially those containing iron. When iron-bearing minerals like pyroxene or olivine react with dissolved oxygen, they form iron oxides (rust). This produces the characteristic red, orange, and yellow staining seen on many rock surfaces in New York State. The chemical equation for iron oxidation is:

Hydrolysis

Hydrolysis occurs when water molecules actually react with mineral crystal structures, breaking chemical bonds and forming new minerals. The most common example is the hydrolysis of feldspar (the most abundant mineral in Earth's crust) into clay minerals:

Factors Affecting Chemical Weathering Rate

Several factors influence how quickly chemical weathering occurs. Temperature increases the rate of chemical reactions — for every 10°C rise, reaction rates roughly double. Moisture is essential since water is a reactant. Surface area plays a critical role: mechanical weathering that breaks rock into smaller pieces exposes more surface area for chemical attack. This is why mechanical and chemical weathering work together as a system.

The "Ripple Effect" — How Water Connects Earth Systems

The title of the state lab — The Ripple Effect — reflects a powerful idea: a single drop of water can trigger a cascade of changes that ripple through multiple Earth systems. The hydrologic (water) cycle and the rock cycle are not separate systems — they are deeply interconnected, and water is the link.

The Hydrologic Cycle

Water moves continuously through Earth's systems. It evaporates from oceans, lakes, and rivers. It transpires from plants. Water vapor rises, cools, and condenses to form clouds. Precipitation falls as rain, snow, sleet, or hail. Once on the surface, water may infiltrate into the ground (becoming groundwater), run off over the surface into streams and rivers, or be stored temporarily as snow and ice. Each of these processes interacts with Earth materials.

Water Drives the Rock Cycle

Water is the primary engine that drives the surface processes of the rock cycle:

New York State: A Living Laboratory

New York State's landscape is a textbook example of water's work. The Finger Lakes were carved by glacial ice (frozen water) during the last Ice Age. The Hudson River Valley was eroded by running water over millions of years and later modified by glaciers. The Catskill Mountains show deep gorges cut by stream erosion. Long Island is entirely composed of sediment deposited by glacial meltwater. Even New York City sits on bedrock that has been shaped by water over hundreds of millions of years.

When you perform The Ripple Effect lab, you will observe these same processes at work — investigating how water weathers, erodes, transports, and deposits Earth materials, and how the hydrologic and rock cycles are connected through these interactions.