Recent Changes

{mechanical_weathering.jpg} Mechanical Weathering: Unloading- Sheeting is occuring, can see the onion-like layers
{276.jpg} Chemical Reaction: Hydrolysis- Reation when acid rich water is added
{oxidation-316.jpg} Chemical Weathering: Oxideation- Rust on iron when oxygen is added as seen in the picture when it got wet

{Mechanical_weathering_2.jpg} Mechanical Weathering: Frost Wedging- the rock is split into segments in this picture and is divided into 4 pieces
{mechanical_weathering.jpg} Mechanical Weathering: Unloading- Sheeting is occuring, can see the onion-like layers
{276.jpg} Chemical Reaction: Hydrolysis- Reation when acid rich water is added

Igneous Activity at Convergent Plate Boundaries
Volcanic island arcs- also called island arcs
-those that develop within the ocean and grow large enough for their top to rise above the surface
-Dominated by the eruption of fluid basalts that build numerous shieldlike structures on the ocean floor
Continental Volcanic arc-produced by slabs of oceanic lithosphere subducted under continental lithosphere
-continental crust is thicker + higher silica
Intraplate Igneous Activity
Mantle Plum- ascends toward the surface
-responsible for vast outspourings of basaltic lava that create large basalt plateaus
-appear to form deep within the earths core
-sold rock that rises to the surface
Hot Spot- Magma that triggers volcanism at the surface
-more than 40 have been identified

Nature of Plutons
-known to occur in a great variety of sizes and shapes
-some structures have a tabular (tabletop) shape, some being massive in size
-classified by their shaps either tabular or massive
-Plutons are discordant or to disagree if they cut across existing structures
-Concordant or to agree if they form parallel features
Dikes
-are tubular discordant bodies that are produced when magma is injected into fractures
-great enough to seperate the walls of the fracture further
-often found in groups that once served as veritcal oriented pathways followed by molten rock that fed ancient rock flows
Sills and Laccoliths
-Sills are tubular plutons formed when magma is injected along sedimentary bedding surfaces, mostly common when horizontal
-Laccoliths are similar to sills because they form when magma is intruded between sedimentary layers in a near surface environment
Batholiths
-Largest intrusive igneous bodies
-occur as linear structures several hundreds of kilometers long and 100 killometers wide
Stocks- appear to be portions of batholiths that are not yet fully exposed
-consists of rock types having chemical compositions toward the granatic end of the spectrum
-may compose the core of mountain systems