Geology: Igneous Rocks, Weathering, and Sedimentary Processes

Vocabulary flashcards covering key concepts from lecture material on igneous composition sources, physical and chemical weathering processes, Snowball Earth history, and clastic sedimentary rock classification.

Basaltic Melt

A type of molten rock generated specifically from the partial melting of the Earth's mantle.

Rhyolitic Melt

A type of molten rock generated specifically from the partial melting of the continental crust.

Andesitic Melt

A molten rock composition that specifically indicates formation at a convergent plate boundary.

Physical Weathering

The physical and mechanical breakdown of rock into smaller particles through fracturing and crumbling without altering its chemical composition.

Chemical Weathering

The breakdown and dissolution of solid rock through chemical reactions involving water and atmospheric gases.

Frost Wedging

A physical weathering process where water enters cracks in rock, freezes, expands by approximately $11\%$ in volume, and forces the crack wider.

Root Wedging

A physical weathering process where plant roots grow into rock cracks, expand as they mature, and exert outward force that breaks the rock apart.

Release of Confining Pressure

A physical weathering mechanism where deeply buried rock expands elastically and cracks as overlying rock is stripped away by erosion.

Bowen's Reaction Series

A framework showing mineral stability at specific crystallization temperatures, explaining why high-temperature minerals like olivine are extremely unstable and susceptible to chemical weathering at Earth's surface.

Ocean Salinity

The concentration of ions in seawater, derived primarily from the chemical weathering of surface silicate minerals transported continuously by river runoff.

Drop Stones

Large rock fragments transported by glaciers and icebergs into marine environments, which sink into soft ocean floor sediments as icebergs melt.

Rodinia

An ancient supercontinent existing around $700\,\text{million}$ years ago where most of Earth's continental landmasses were grouped near the equator.

Snowball Earth

A phenomenon roughly $700\,\text{million}$ and $600\,\text{million}$ years ago where extreme chemical weathering of equatorial bare rock drew atmospheric $CO_2$ down to $\approx 100\,\text{ppm}$, triggering runaway global glaciation.

Lithification

The geological process of converting loose sediment into solid rock through compaction and mineral cementation.

Clastic Sedimentary Rocks

Sedimentary rocks composed primarily of weathered particles or fragments derived from previously existing rocks.

Clast

An individual particle, grain, or fragment of rock contained within a clastic sedimentary rock.

Conglomerate

A clastic sedimentary rock composed predominantly of rounded or angular rock fragments larger than $2\,\text{mm}$ in diameter.

Sandstone

A clastic sedimentary rock composed of visible sand grains ranging in size from $\frac{1}{16}\,\text{mm}$ to $2\,\text{mm}$ in diameter.

Siltstone

A clastic sedimentary rock composed of silt particles ranging from $\frac{1}{256}\,\text{mm}$ to $\frac{1}{16}\,\text{mm}$ in diameter, which feel gritty when ground against teeth.

Shale

A fine-grained clastic sedimentary rock made of clay particles smaller than $\frac{1}{256}\,\text{mm}$ in diameter, characterized by a smooth feel.