Presentation is loading. Please wait.

Presentation is loading. Please wait.


Similar presentations

Presentation on theme: "SEDIMENTARY ROCKS, METAMORPHIC ROCKS, AND AGE DETERMINATION."— Presentation transcript:



3 SED-MET ROCKS-AGE Sedimentary rock family Definition and Explanation comprised of sediments accumulated from physical and or chemical processes mostly in large bodies of water consolidated through lithification

4 SED-MET ROCKS-AGE Factors and concepts related to rock formation weathering--”breaking down” of rock materials at or near surface of Earth chemicalchemical--decomposition of materials and formation of new substances through removal of or additions to the weathered material physical or mechanicalphysical or mechanical--disintegration of materials with no new substances forming

5 SED-MET ROCKS-AGE Erosion removal or transportation of material by stream water, glacial ice, wind, and gravity eroded materials may eventually accumulate in large amounts Lithification compaction and cementation of sediments to become rocks

6 SED-MET ROCKS-AGE Stratification accumulations in layers (strata or beds) and is the most common occurrence of this family of rock Law of superposition in a series of strata, each layer is older than the one above and younger than the one below--this reflects a relative age relationship between layers

7 Stratification in Sedimentary Rocks


9 SED-MET ROCKS-AGE Sedimentary rock types three types based on the way they form; clastic (detrital), chemical inorganic, and organic clastic sediments accumulated primarily by physical processes as deposits from stream water, glacial ice, wind, etc. then lithified to rock

10 SED-MET ROCKS-AGE Wentworth’s sediment size classification is used to name the specific clastic rock in the detrital class

11 Wentworth’s Scale of Sedimentary Particles

12 Different colors of beach sand in the world


14 Detrital (Clastic) Sedimentary Rocks Larger grained Conglomerate Breccia

15 Detrital (clastic) Sedimentary Sandstones Graywacke Arkose Quartz Sandstone

16 Detrital (clastic) Sedimentary Rocks Smaller Grained Siltstone Claystone Shale

17 SED-MET ROCKS-AGE biological (organic) rocks accumulation of animal shells or plant material then lithified--particle size is not important in naming biological rocks


19 White Cliffs of Dover SED-MET ROCKS-AGE

20 buried plants lignite bituminous COAL SERIES anthracite methane coal gas Peat

21 SED-MET ROCKS-AGE Biological (organic) formed chert

22 SED-MET ROCKS-AGE chemical (inorganic) rocks formed from chemical reactions in the oceans or large bodies of water


24 Lakes formed from Glaciation Lake Bonneville

25 Evaporite deposits in Death Valley, California

26 SED-MET ROCKS-AGE Chemically (inorganic) formed chert---nodules of chert caused by replacement of silica for bedrock—is present in the local Burlington limestone bedrock in this area

27 SED-MET ROCKS-AGE Some special features in sedimentary rocks cross bedding relatively thin layers inclined at an angle to the main bedding formed by currents in water or wind

28 Cross bedding

29 SED-MET ROCKS-AGE graded bedding a sedimentary layer characterized by a decrease in sediment size from bottom to top ripple marks small waves of sand that develop on surface of sedimentary layer by the action of moving water or wind

30 Ripple marks

31 SED-MET ROCKS-AGE Significance of sedimentary rocks only family of rock containing an abundant record of life forms and the changes in life forms throughout geologic time only family of rock in which natural gas, petroleum and coal are formed and found used as building materials, tombstones and some limestones are used as a source of lime

32 Groundwater Petroleum and Natural Gas Coal

33 Cement from Limestone Salt Uranium

34 SED-MET ROCKS-AGE Metamorphic rock family Definition and explanation formed primarily through action of temperature and/or pressure on preexisting rocks little or no melting during process time is also an important factor rocks will loose evidence of fossils or other features present before the change

35 SED-MET ROCKS- AGE Types of metamorphism contact or thermal usually forms with intrusions of smaller rock bodies as stocks in country rocks temperature associated with the intrusive body is the prime metamorphic agent—lower temperatures would form lower grade of metamorphic rocks

36 SED-MET ROCKS-AGE regional metamorphism usually forms with intrusions of larger bodies like batholiths or laccoliths temperature and pressure are equally important in the metamorphic process and includes a much larger area of metamorphism—higher temperatures would form a higher grade of metamorphic rock

37 SED-MET ROCKS-AGE Kinds of metamorphic rocks all but one rock is comprised of silicate minerals foliated minerals are aligned in a pattern

38 Foliated metamorphic rocks

39 Foliated or Lineated Metamorphic Rocks Gneiss Slate Schist Phyllite

40 Nonfoliated metamorphic rocks

41 Non foliated Metamorphic Rocks Quartzite (from arkose) Marble

42 SED-MET ROCKS-AGE Important uses building materials and tombstones marble can be used in art as a sculpturing material

43 SED-MET ROCKS-AGE Age determination (geologic age) important concepts used relative age concepts crosscutting and intrusive nature of igneous rocks law of superposition pertaining to sedimentary rocks absolute age dating determination of amounts of radioactive parent and stable daughter

44 Relative Age dating

45 SED-MET ROCKS-AGE Age determination method relative and absolute age determination methods are used together to establish the absolute age of rocks which cannot themselves be dated igneous rocks are the best rock family to use in absolute age determinations Index fossils are used to facilitate the determination of the age of sedimentary rocks

46 Determine the absolute age of sedimentary bed, B given: 1. igneous intrusive, V dated at 2.15 million years old 2. lava flow, P dated at 2.25 million years old (both V and P were dated using the absolute age determin- ation method we discussed in the mineral section)

47 Correlation of Index Fossils From 2 Different Areas


Similar presentations

Ads by Google