Wellesley Elementary Schools

1. Wellesley Elementary Schools Grade Four Geology Training By: Lisa Moore

2. Training Objectives • To provide necessary information for parent volunteers, in preparation for leading students on the fourth grade geology field investigation. • To familiarize parent volunteers with important geological sites in Wellesley.

3. Presentation Outline • Background information – Layers of the earth, plate tectonics, the rock cycle • Mineral identification • Three types of rocks – Igneous, Sedimentary, and Metamorphic • Geologic time scale – Geologic history of Wellesley

4. The layers of the earth • Crust – Relatively cold, thin, brittle solid, fractures with earthquakes. Made of calcium, sodium, and aluminum silicate minerals. 5-20miles(8-32km) thick, thickest at mountains, thinnest at ocean floor • Mantle – An elastic solid, making up most of the Earth’s mass. Made of iron, magnesium, Aluminum, silicon, and oxygen. Convection currents within mantle cause crustal plates to move.(1832 F or 1000 C), 1800miles (2896km) thick • Liquid outer core – Made of iron and sulfur.(6692 F or 3700 C), 1400miles (2252km) thick • Solid inner core – Made of iron. Remains solid due to immense pressure, even at high heat. (9000 F or 5000 C), 800 miles (1287km) to center

5. Plate Tectonics • Plate tectonics is the movement of the earths crustal plates due to convection currents in the mantle. As plates move they may collide, pull apart or rub past each other. The earth’s land masses sit atop these crustal plates and are deformed by crustal motion. • Demo mantle elasticity. • Demo plate tectonics.

6. Tectonic plate boundaries and the Pacific ring of fire

7. Minerals – Naturally occurring, homogenous, inorganic solid with definite chemical composition, crystal structure and specific physical properties • Minerals are the building blocks for all rocks. • A mineral may be a pure element, like gold or a complex compound, like quartz. • A rock is made up of one or more minerals physically or chemically combined. The type of rock formed will be determined by the type of minerals present and how it was formed. • Scientists use characteristics of crystal shape, color, luster, hardness and streak to identify minerals. • Demo mineral identification techniques.

8. Three types of rocks • Igneous – formed when molten rock, magma or lava, cools and hardens. • Sedimentary – formed when sediments are compacted and cemented together. • Metamorphic – formed when existing rock is put under intense heat and pressure, physically or chemically changing the rock.

9. The rock cycle - a model that shows how minerals are recycled through continuous geologic processes on earth.

10. Igneous rocks - from Latin meaning fire • Intrusive igneous rock – formed from magma deep within the earths crust. These rocks cool slowly, resulting in coarse grained texture with large visible crystals. (granite and diorite) • Extrusive igneous rock – formed when lava cools at the earth’s surface. These rocks cool quickly, resulting in a fine grained or smooth texture. Air bubbles may be present. (basalt, obsidian, pumice)

11. Extrusive igneous rock examples: Top left is a lava flow & below it is Basalt Intrusive igneous rock examples: Top right is Granite & below it is an igneous intrusion

12. Sedimentary rock • Made from sediments; bits and pieces of rock and organic matter, being cemented and compacted together • Sediments transported by wind, water, and glaciers • Evidence of layering, ripple marks, fossils, and rounding of particles of sediment

13. Sedimentary rocks – Breccia, a fossil, Roxbury puddingstone, sandstone

14. Metamorphic rock • Formed when existing rock is put under intense pressure and/or heat and is changed physically and/or chemically. • Regional metamorphism and contact metamorphism. • May see banding, rock is very hard.

15. Examples of metamorphic rock and what they changed from.Top: left is the igneous rock granite, at right after heat and pressure, becomes gneissBottom: left is sedimentary shale, at right after heat and pressure becomes slate

16. Can you name the types of rock seen below?

17. The geologic time scale : A trip through Wellesley’s geologic history

19. Word bank of terms to know • Rock • Mineral • Crystal • Crust • Mantle • Intrusive igneous rock • Extrusive igneous rock • Sedimentary rock • Metamorphic rock • Bedrock • Weathering • Erosion

20. Final thoughts: • Every rock tells a story of how it formed and what has happened to it. • Don’t worry about specific rock names but be able to look for identifying traits for each type of rock. (Igneous – visible crystals, Metamorphic – banding, Sedimentary – layers, fossils, rounded particles) • Understand what a rock, or rock formations, tell you about the geologic history of the area. (i.e. glacial activity, volcanic activity, crustal motion, water action) • Generate excitement and curiosity as you learn about Wellesley’s history through its rocks, exploring it’s volcanic past, glacial past and present day geology.

21. Jany_Finkielsztein@wellesley.k12.ma.us 781 446 6210 xt 1411 Outdoor: Friday October 15, Tuesday October 19, Friday October 22 and Tuesday October 26 (8:50-11:45am, meet at Kelly Memorial Park on Elmwood next to the Baptist Church) Geology Video