Presentation on theme: "Chapter 7 Mountains and Hills Pg 144. Quiz 7a ________ is the variety of elevation's and arrangement of land forms. _______is made of lighter, less-dense."— Presentation transcript:
Chapter 7 Mountains and Hills Pg 144
Quiz 7a ________ is the variety of elevation's and arrangement of land forms. _______is made of lighter, less-dense rocks and is generally much thicker. _________is thinner and more dense than continental crust ______________A natural elevation of the earth’s surface rising into a summit. __________The shapes of the structures on the earth’s surface is known as Mountainous areas have__________, while plains and plateaus have__________________. Name two types of landforms____________________
7A What is a Mountain? Topography - is the variety of elevation's and arrangement of land forms. Basins are formed when oceanic crust sinks into the mantle. 7qhUQZg 7qhUQZg
Continental crust is made of lighter, less- dense rocks and is generally much thicker it rises higher above sea level and makes the land we walk on. Oceanic crust is thinner and more dense than continental crust. This crust produces the ocean floor. Isostasy- describes the balance of the weights of rock, water, and ice and the upward force of the mantle
Landforms and Orogeny The shapes of the structures on the earth’s surface is known as landforms Landforms include: beaches, valleys, plains, deserts, lakes, and plateaus. Orogeny- having to do with the making of mountains through tectonic processes. hqnnTVk hqnnTVk
Elevation and Height Mountain - A natural elevation of the earth’s surface rising into a summit. Difference between a hill and a mountain is mostly height. The definition for each is based on local customs. Summit- highest point on a hill or mountain. We measure mountains in meters of feet above sea level or mean sea level. Elevation - the measure of a mountain using sea level as zero height(Feet above sea level)
Actual height- of a mountain is the height of its summit above the lowest elevation of the surrounding terrain, or its base. It measures height from the mountain base. Terrain - the nature of the surrounding land. Base - lowest elevation of nearby terrain from which the mountain rises to a peak. Relief - the difference in height between the highest and lowest elevations. Mountainous areas have high relief, while plains and plateaus have low relief.
Groups of Mountains Mountains exist in groups or by themselves. Mountain Range- A series of mountain peaks in the same geographical area. Mountain system- A group of mountain ranges connected over a much larger area.
7.B Tectonic Mountains Tectonic mountains also form at Divergent zones. The mid- Ocean ridge seems to exist because tectonic forces are slowly pulling rocks apart. Tectonic mountains are created when tectonic plates collide, pull apart, lift up, or subside
7.7 Fold mountains Sediment- is a deposit of eroded earth materials. It collects in low spots, usually in streambeds can also be carried and deposited by ice or wind. When water deposits sediment it forms a flat layer. Fold Mountains- mountains that form from folded rock strata.
Anticline - arch of rock layers. The layers of rocks have been pushed into an upward force. Syncline - is a trough or downward fold of rock strata formed just like an anticline. Monocline- a motion that smoothly folds the strata above the fault into a single step. When two tectonic plates converge it produces piles of mountains with complex folds and faults.
7.8 Rift Valleys Rift- a series of steep-walled valleys lined with high cliffs rising from faults parallel to the valley. Most are located at mid ocean ridges between diverging oceanic plates Grabens- a steep- sided valley framed by normal faults parallel to the length of the valley.
Fault-block mountains- mountains set apart by one or more normal faults. Are formed when tectonic forces exert in opposite directions. Geologic province- is a region with characteristics that separate it from surrounding terrain. Plateaus- are broad regions of relatively undisturbed sedimentary deposits lifted by some tectonic process. Many mountains today are plateaus. Dome- is a landform with sedimentary strata that looks like an upside down bowl. Forms When magma underground pushes up. Basin- is the opposite of a dome. Form when a magma chamber deep underground emptied.
Volcanoes and seamounts are mountains with deep tectonic activity that produces molten rock.
7c Non tectonic hills and mountains Erosions - carries away particles by wind, gravity, flowing water, or wind to another location. Erosions affects mountain, valleys, and shorelines. Erosions affects all rocks after they form. Deposition -Sediments deposited to lakes underline the bottom of the lake. The sediments build up over time.
7.14 Erosional mountains- these mountains are carved by extensive erosion. Some parts of the mountain remain intact. The mountain contains harden lava. Mesas- In western United States these hills are broad, flat-topped hills remaining from the erosion. Have steep cliff like sides Buttes-smaller flat topped hills. Have steep cliff like slides. Talus- piles of rock that collect at the bottom of a cliff. Pinnacles- tall spires of rock that remain from eroded plateau. Can be found alone or in groups called fins.
Monadnocks- is solidified magma that formed domed rock islands standing out of a flat plain surrounding them. Monadnocks consist of a massive erosion resistant structure that formed beneath softer sediment Stone arches are found along with fins and pinnacles. Volcanic necks are all that remains of ancient volcanoes. As a volcano erupts and builds the mountain, the magma tube that leads to the crater grows. If the volcano goes extinct the magma hardens and remains in the mountain.
7.15 Depositional mountains- sediments build up on land and other landforms. Sand dunes- made by wind depositing sand which create hills of sand. Glacier till- is made up of rocks, gravel, sand, and silt taken up and pulverized by a glacier’s motion. Volcanoes are considered depositional mountains because they build up when liquid and solid rock materials from eruptions are deposited on the earth’s surface.