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 Stock> Domed mountains create:
Cuestas Hogback ridges Flatirons Watergaps Stocks Dike Dike Sopris is NOT a volcano- Its 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 earths 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 earths crust are folded and/or faulted then are uplifted and eroded.The Rockies are an example. Erosion When a section of the earths 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- -deepestlake in the world -5,315 feet deep -contains 1/5 of all the worlds freshwater Lake Tahoe