9/2/14 Lecture 3 ● All teachers: ○ Johann Gottlob Lehmann  Berlin 1756 ○ Giovanni Ardvino  Padua 1760 ○ Abraham Gottlob Werner  Freiberg 1790 ● Each scheme reflected in its details the lithologic sequence of strata in the geographic area familiar to its author ○ names given by Ardvino ● Time Scales ○ 4. Quaternary or Alluvial ■ loose sediments at low elevations, unimportant modern deposits ○ 3. Tertiary ■ low mountains and foothills composed of poorly lithified sedimentary strata and volcanics, highly fossiliferous ○ 2. Secondary ■ lower mountains, composed of welllithified fossiliferous sedimentary rocks, especially limestones, sandstones, and coal ○ 1. Primary or Primitive ■ crystalline (plutonic igneous and metamorphic); granite, schists, gneisses ■ formed at Creation, now exposed at highest mountains ● Abraham Gottlob Werner ○ 1790 Founder of Neptunism ○ developed classification of 5 great “formations” ● Werner’s Time Scale ○ 5. Vulkanishe: volcanic rocks ○ 4. Aufgeschwemmtgebirge: unimportant alluvial depositis ○ 3. Floetzgebirge (flood mount): sandstone, coal, lime stone; deposits under changing conditions as ocean retreated ○ 2. Transition: shale, slate; formed during transition of earth from uninhabitable to inhabitable condition ○ 1. Primitive: granite, gneiss, schist, no fossils; precipitated from universal ocean ● Neptunism predicts: ○ all rocks are aqueous precipitates ○ strata accumulated in order, as universal order withdrew ■ oldest layer found everywhere ■ younger layer still covered by ocean ● Neptunism: ○ proved wrong, over and over ■ students discoered Werner was wrong ■ using superposition, crosscutting relations, and fossil succession ● Werner Vocab: ○ Drift: rocks dropped from icebergs ○ Formation: major chapter of Earth’s history ● Our Vocab: ○ Drift: glacial moraine ○ Formation: local rock unit ● Neptunism vs. Plutonism ○ debate centered on basalt: igneous or sedimentary ■ Italians: igneous lava ■ Werner: sedimentary ○ Chaine des Puys: mountain chain in France ○ Nicholaus Desmarest: wondered if Chaine des Puys was a volcano. The whole mountain was basalt. ● James Hutton: ○ 1790 Theory of the Earth ○ British founder of Plutonism ○ Huttonian philosophy: ■ explained all past events by reference to geological processes active today ■ apparently weak natural forces can produce the same changes as catastrophic events ■ first to use extended geological time ■ established the basis for Modern Uniformitarianism ○ igneous origin of basalt ■ fluid intrusive origin ○ crystalline rocks aren’t the oldest rocks ■ granites are younger rocks they intrude ■ oldest rocks are metasedimentary rocks ○ the Sedimentary Cycle ■ terrestrial weathering and erosion, sedimentary transport, deposition, lithification, uplift to make new land ○ mountain building is ongoing in Earth history ○ dynamic equilibrium: longterm planetary balance between constructive and destructive process ● Siccar Point ○ Hutton’s great unconformity ○ Old red sandstone unconformably overlies folded silurian strata ● Dynamic equilibrium: destructive vs. constructive ○ all processes act throughout history ○ no evidence for origin or end of Earth ○ streams carve their own valleys (not flood) ○ mountains form by convulsions of crust (not flood) ● “In the economy of the world, I can find no traces of a beginning, no prospect of an end” ● John Playfair ○ 1802 ○ illustrations of the Huttonian Theory of the Earth ○ Established the Huttonian philosophy as foundation of modern geology ● Catastrophism ○ emerged in 19th century France in opposition to Huttonian philosophy ■ Georges Cuvier with Alexandre Brongiart and Algide D’Orbigny ■ mapped Creataceous tertiary strata of Paris Basin ■ strata are laterally continuous up to 75 miles but in same vertical order ■ successive formations have different fossils ■ once extinct, species never reappear. Extinctions are real ○ Earth has multiple chapters (stages) ○ with sharp boundaries, produced by sudden powerful events: revolutions! ○ Cuvier classified Earth into 30 stages ● Sir Charles Lyell ○ adopted Huttonian philosophy ○ emphasized uniformity of geologic processes ○ principles of Geology, 1839 ■ first english textbook on geology ○ Goal: to achieve a body of “settled principles” ■ to establish geology as a science ● Lyell’s uniformity ○ actualism: present is key to past; focus on similarities, not differences ○ is a steadystate system to indefinite age ■ refused to consider that any process not acting today could have been important in past ○ today we recognize that many geologic processes are more or less important than in past ● Charles Darwin ○ Beagle voyage 183135 ■ adopted Lyell’s extended time scale ■ was the first to recognize that that the fossil record is ion complete because the only sedimentary rock record is incomplete has unconformities ○