The document discusses the rock cycle and how rocks are formed. It explains that igneous rocks form from the cooling of magma, either underground to form intrusive rocks or above ground to form extrusive rocks. Sedimentary rocks form from the weathering, erosion, deposition and compaction of other rocks. Metamorphic rocks form from the alteration of existing rocks through heat and pressure in the Earth's crust. The rock cycle involves the interconversion of these three main types of rocks through various geological processes.
this presentation is all about weathering, erosion, & mass wasting. this may be simple, but it is good for the eyes, and the information is short but complete. :))
The continental crust covers nearly a third of the Earth’s surface, extends vertically from the Earth’s surface to the Moho discontinuity.
It is less dense than oceanic crust.
Compositionally is dominating by silicate elements
Models for the differentiation of the continental crust shows when and how it was formed
Reconciling the sedimentary and igneous records indicates that it may take up to one billion years for a new crust to dominate the sedimentary record.
The continental crust of the Earth differs from the crust of other planets in the Solar System
Its formation modified the composition of the mantle and the atmosphere
It supports life
And it remains a sink for CO2
Evaluating the composition of new continental crust can provide important clues as to how and when it may have been generated. Which is required understanding the differentiation processes of igneous (granites) and sedimentary rocks
This is the summary on gateway 1 on plate tectonic. It discusses about the following:
1) Characteristics of the different structure of the earth.
2) The mechanism leading to plate movement
3) Landforms associated to the different plate movement.
Weathering is an important geological mechanism which can destabilize the earth’s surface materials and remove them by erosive processes. Weathering is the physical disintegration and chemical decomposition of a rock mass on the land. It is a unique phenomena happening on the earth’ surface. Weathering is a collective term used to denote the mechanical, chemical and biological(organic) processes that take place on the earth’s surface. Weathering of rock-forming minerals can create new products from pre-existing rocks. In many regions, soils are the ultimate products of weathering. Weathering of rocks releases chemical compounds that become available for biological processes. It is necessary to study the factors that are influencing the weathering processes.
this presentation is all about weathering, erosion, & mass wasting. this may be simple, but it is good for the eyes, and the information is short but complete. :))
The continental crust covers nearly a third of the Earth’s surface, extends vertically from the Earth’s surface to the Moho discontinuity.
It is less dense than oceanic crust.
Compositionally is dominating by silicate elements
Models for the differentiation of the continental crust shows when and how it was formed
Reconciling the sedimentary and igneous records indicates that it may take up to one billion years for a new crust to dominate the sedimentary record.
The continental crust of the Earth differs from the crust of other planets in the Solar System
Its formation modified the composition of the mantle and the atmosphere
It supports life
And it remains a sink for CO2
Evaluating the composition of new continental crust can provide important clues as to how and when it may have been generated. Which is required understanding the differentiation processes of igneous (granites) and sedimentary rocks
This is the summary on gateway 1 on plate tectonic. It discusses about the following:
1) Characteristics of the different structure of the earth.
2) The mechanism leading to plate movement
3) Landforms associated to the different plate movement.
Weathering is an important geological mechanism which can destabilize the earth’s surface materials and remove them by erosive processes. Weathering is the physical disintegration and chemical decomposition of a rock mass on the land. It is a unique phenomena happening on the earth’ surface. Weathering is a collective term used to denote the mechanical, chemical and biological(organic) processes that take place on the earth’s surface. Weathering of rock-forming minerals can create new products from pre-existing rocks. In many regions, soils are the ultimate products of weathering. Weathering of rocks releases chemical compounds that become available for biological processes. It is necessary to study the factors that are influencing the weathering processes.
Over the last decade, demand for spring management has increased as traditional spring sources have started drying up or becoming contaminated. In response, communities, NGOs and state agencies began dedicated spring protection programmes. In the Himalayas, the State of Sikkim and organizations such as Central Himalayan Action and Research Group (CHIRAG) and People Science Institute (PSI) started identifying and protecting spring recharge areas around 2007. The difference between these programmes and many other previous efforts is that they went beyond supply-side improvements to focus on the use of hydrogeology to map springsheds for targeted interventions.
The Advanced Centre for Water Resources Development and Management (ACWADAM), a research and capacity-building organization comprised of hydrogeologists and other experts began lending their expertise and building capacity of stakeholders. ACWADAM provides technical support, training and materials in hydrogeology to all network partners as well as others in India and the region. Similar programmes began independently in most of the mountain regions of India. Arghyam, a funding organization that was supporting many of these programmes, noticed that these disparate initiatives shared commonalities despite geographic diversity. They thus organized and funded a meeting of these various organizations in June 2014, and the Springs Initiative was born.
The springs initiative aims to tackle the current water crisis and to ensure safe and sustainable access to water for all, by promoting responsible and appropriate management of aquifers, springsheds, and watersheds and conserving ecosystems in partnership with communities, governments and other stakeholders.
This presentation has been developed as a part of the springs initiative to promote an understanding of springs and their role in mountainous areas.
2. How do we Learn about
Earth’s History?
• Archeology
– The study of human life on Earth
– Artifacts: objects made by humans such as tools,
weapons, containers, etc.
• Paleontology
– The study of life's history as revealed in the preserved
remains of once-living plants and animals
– Fossils: Any evidence of organisms that once lived on
Earth
• Geology
– The study of Earth's origin, history and structure
– Rocks: solid masses of mineral matter (including
metals, stones & gems)
6. Crystallization
• Magma (melted rock from Earth's mantle)
cools with a regularly repeating (lattice)
structure to form IGNEOUS rocks.
• Intrusive:
under-
ground
• Extrusive:
above
ground
7. Intrusive
(underground)
Slow
Large
Crystallization
Crystals
MAGMA
9. Igneous Intrusions
• Dike: “veins” that run perpendicular to (cut through) the strata
• Sill: sheets that run in the same direction (between) the strata
• Batholith: huge, bulbous mass intruding surrounding strata deep underground
29. Deposition of Sediment
Along with erosion, rocks and rocky particles (such
as shell and bone) are transported and/or
deposited in layers (called strata) by:
• Icebergs (former glaciers) melting
• Settling of biogenic ooze
• Earthquakes
• Volcanic eruptions
• Floods and Hurricanes
• Evaporation
30. Mt. St.
Helens
before
eruption
Mt. St.
Helens
after
eruption
32. Burial and Compaction
• Layers of sediment are
laid down on each other
• Particles of sediment
are squeezed together
by the weight of water
and layers above
• Solid minerals form in
the spaces between
sediment particles,
holding them together
• This process is also
known as lithification
33. Sedimentary Rocks exhibit the following:
• Stratification: the
deposition of sediment
into horizontal layers or
“strata”
• Lamination: several
thin layers (< 1cm)
• Superposition: deeper
layers are older
• Cross-cutting
Relationships:
intrusions younger than
the strata they cut
through
• Fossils: evidence of life
trapped in rock layers
37. Deformation
Intense forces deep underground can twist, fold, or tilt
existing rock into different shapes.
Causes:
• Pressure from slow,
deep folding as tectonic
plates collide
• Tension from tectonic
plates pulling away from
one another
• Shear from rapid surface
movement along fault
lines during earthquakes
38. • Experiment
using layered
sheets of wax
– shows how rock
layers tend to
bend and fold
before they
break
41. Metamorphism
A change in mineral composition of existing rocks due to
extreme pressure and/or heat deep within the Earth’s
crust.
Metamorphism
• Regional: large animation
area such as
mountain range in
subduction zone
where rocks are
pulled/pushed
• Contact: due to
physical proximity of
heat, usually from
magma intrusion
42.
43. Metamorphic Rocks - the hardest type
of rocks found on earth
Marble Gneiss
Quartzite
Schist Slate
48. Review: Major Rock Groups
• Igneous
– Formed from magma (molten rock)
– Intrusive (plutonic): slowly cool underground
– Extrusive (volcanic): quickly cool at the surface
• Sedimentary
– Form in layers at Earth’s
surface, usually under
water
– Contain fossils
• Metamorphic
– Rocks changed by pressure
and temperature
50. In Conclusion…
• The rock cycle
demonstrates the
relationships among the
three major rock groups
• It involves processes on the
Earth’s surface as well as
the Earth’s interior
• It is powered by
– the interior heat of the Earth
– earth’s gravitational forces
– energy from the sun
• It connects the “hydrologic
cycle” with the “tectonic
cycle”
Editor's Notes
Anybody know what type of rocks these are?
solid Iron inner core, liquid outer core, semi-solid Mantle (magma)
Crystal structure can be cubic, hexagonal, orthorhombic, tetragonal, octahedral, etc.
The slow cooling formed rocks with large crystals. Granite is an example of a rock that cooled slowly and has large crystals.
Granite
Basalt is an example of this type of rock. Obsidian is an example of another extrusive igneous rock that cooled so fast that it has no crystals and looks like shiny, black glass. Pumic and Scoria - bubbles trapped in the lava form holes as the rock cools too quickly for the gasses to escape.
Incandescent lava fountains play above an eruptive fissure at Krafla volcano in NE Iceland on September 6, 1984. After a quiet interval of 33 months, an eruption began on September 4 along a fissure extending from Leirhnjúkur 8.5 km to the north. Initially, the fissure was active along its entire length, but later lava production was highest at the northern end of the fissure.
Shield volcanoes derive their name from their low-angle profile , which resembles the broad shields used by Hawaiian warriors. They are formed primarily by the successive accumulation of fluid lava flows, which descend from summit or flank fissure systems. Although shield volcanoes are not as visually dramatic as stratovolcanoes, they are often much larger features. Oceanic shield volcanoes such as those in the Hawaiian Islands can rise as much as 8000 m above the surrounding sea floor and 12,000 m above their actual bases, which have sagged due to the immense mass of the volcano. Their volumes can exceed that of stratovolcanoes by several orders of magnitude. Most shield volcanoes are formed of fluid basaltic lava flows. Calderas are large volcanic depressions formed by collapse of the summit or flanks of a volcano into underlying chambers evacuated by very large explosive eruptions or the effusion of large volumes of lava flows. Earth's calderas range from a kilometer to as much as about 100 kilometers in width; many contain scenic caldera lakes. Calderas may be simple structures formed during an eruption that truncates either the summit of a single stratovolcano or a complex of multiple overlapping volcanoes, such as at Crater Lake in Oregon. Other calderas are compound structures formed incrementally as a result of multiple eruption-related collapses, such as the massive 30 x 100 km wide Toba caldera in Sumatra, which was formed during four powerful explosive eruptions during the Pleistocene. Calderas are most often defined as depressions produced as a result of large-scale eruptions, but the word has also been used as a morphological term that encompasses volcanic depressions formed by erosion or large volcanic landslides. Stratovolcanoes (also known as composite volcanoes) are what most people associate with the word volcano. These towering peaks rise hundreds to several thousand meters above their surroundings, often visually dominating the landscape around them. As their name implies, they are formed of stratified layers of both viscous lava flows and fragmental material. Classic symmetrical stratovolcanoes such as Shishaldin in the Aleutian Islands and Mayon in the Philippines are the exception rather than the rule. Most stratovolcanoes are complex structures formed by multiple eruptions from summit and flank vents. Compound stratovolcanoes may form when the focus of eruptions shifts, forming multiple overlapping edifices. Some stratovolcanoes may form in a few thousand years, but may remain active for tens to hundreds of thousands of years. During their lifespans, dormant intervals may also last tens of thousands of years.
Which of these would be considered “Biological” weathering? Exfoliation is most common in granite (intrusive igneous); because of it's lattice structure (due to crystallization), sheets will fracture and "peel" parallel to the rock surface.
Any Biological weathering here? Lichen on rocks secrete a chemical that slowly eats away at the minerals. Rust = a chemical reaction where iron reacts with water and/or oxygen to form ferric iron oxide (hematite).
Erosion and Weathering affect grain shape: When a rock first breaks, it is very sharp. We call this angular grain shape. <DEMONSTRATION: Break a rock into pieces by pounding on it with a hammer. Get a volunteer from the class to take a few whacks. NOTE! Always wear safety glasses because splinters of the rock really do come flying out. The demonstration should be done at least 10 feet from the nearest student who is not wearing safety glasses. Sparks can fly and this is really cool. Pass around pieces of the broken rock.> Over time, these rough edges get smoothed out. The smoother a rock is, the longer it has been exposed to weathering.
Wind erosion (like that of the dust bowl of the 1930s). Water erosion (roadway is washed away). Glacial erosion (rocks embedded in ice are carried slowly downhill with the weight of the glacier).
Sedimentation rates vary from place to place, and at different times. Rates can range from .2cm to 1 m per 1000 year span.
What do you notice? How much “sediment” do you think was laid down because of this blast? (25 feet thick, with many layers “sifted” by the water)
efinition: Lithification is how soft sediments, the end product of erosion, become rigid rock ("lithi-" means rock in scientific Greek). It begins when sediment is laid down for the last time and is gradually buried and compressed under new sediment. Fresh sediment is usually loose material that is full of open spaces, or pores, filled with air or water. Lithification acts to reduce that pore space and replace it with solid mineral material. The main processes involved in lithification are compaction and cementation. Compaction involves squeezing the sediment into a smaller volume by packing the sediment particles more closely, by removing water from the pore space (desiccation) or by pressure solution at the points where sediment grains contact each other. Cementation involves filling pore space with solid minerals (usually calcite or quartz) that are deposited from solution or that enable existing sediment grains to grow into the pores. The pore space does not need to be eliminated for lithification to be complete. All of the processes of lithification can continue to modify a rock after it has first become a rigid solid. Lithification occurs entirely within the early stage of diagenesis. Other words that overlap with lithification are induration, consolidation and petrifaction. Induration covers everything that makes rocks harder, but it extends to materials that are already lithified. Consolidation is a more general term that also applies to the solidification of magma and lava. Petrifaction today refers specifically to the replacement of organic matter with minerals to create fossils, but in the past it was more loosely used to mean lithification.
Sedimentary rock is the only type of rock to contain fossils! WHY?
Can you guess how each of these was formed? Shoreline ripples, evaporation, conglomerate of river rock, estuary deposit.
Granite to Gneiss When granite is exposed to extreme pressure within the earth, it changes to the metamorphic rock gneiss. Notice how the gneiss has alternating bands of dark and light colors. These bands are made by the minerals in granite becoming realigned by pressure. This online animation shows you what this looks like. Note the effect of confining pressure on how the mineral grains are aligned and compare the alignment of the internal mineral grains to the outward appearance of the rocks. Alternating bands of mineral grains in a metamorphic rock is called foliation. Foliation occurs perpendicular to the direction of stress, as you can see from the diagram below.