Mountains Part II Domed and Fault-Block

Dome Mountains Created when magma pushes up from underneath existing strata and cools.

Associated features: A sill is an igneous intrusion that squeezes in between existing rock layers Goes parallel to the layers The cliff band on Triangle Mtn is a sill A dike is similar but cuts across the existing rock strata The belt on Mt Daly is a dike

Intrusive Magma: Batholiths are large bubbles of magma (usually felsic) that cool underground. Forms Tectonic Domes Smaller bubbles are called Laccoliths- usually a sill that has bulged upwards. Forms Plutonic Domes

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Domed mountains create: Cuestas Hogback ridges Flatirons Watergaps Stocks

Dike Dike Sopris is NOT a volcano- It’s a stock!

Mtn Sopris = Stock

Flat Irons- Boulder

- closest = Grand Hogback near Rifle Hogback- front range - closest = Grand Hogback near Rifle Henry Mtns- laccolith

Cuesta- Horse tooth Reservoir

Historic photo of the Grand Hogback- New Castle

How to tell the difference between a folded and a domed mountain? If the mountain is folded, the underlying rocks will be either sedimentary or metamorphic If the mountain is domed, then the rocks below will be igneous (intrusive/plutonic)

Fault-Block Mountain

Fault Block Mtns Formed from blocks of crust that have been faulted and tilted at the same time. Red Butte Sangre De Cristos Tetons Sierra Nevada Wasatch Mountains

Joints Rock layers may rupture from pressure applied. Fractures where no movement has occurred are called joints,

Faults Faults are fractures in the earth’s crust where movement has occurred. There are three types: normal, reverse or thrust, and strike-slip (also called transcurrent).

Teton Mountains The Tetons in Wyoming have been uplifted along a fault plane.

Basin and range

Mountain Ranges Mountain ranges are formed when long belts of the earth’s crust are folded and/or faulted then are uplifted and eroded. The Rockies are an example.

Erosion When a section of the earth’s crust is elevated, streams begin to erode deep channels. Can form mountains also.

Capstones Resistant layers help to produce mesas, buttes, and pinnacles.

Earthquakes Earthquakes occur due to movement along faults.

Lake Baikal-. -deepest lake in the world. -5,315 feet deep Lake Baikal- -deepest lake in the world -5,315 feet deep -contains 1/5 of all the world’s freshwater

Lake Tahoe