Humid Mophological Systems

A Humid MS is a warm area where the main geological agent is water.

Water acts in three different ways:

• Torrent: Consolidated channels but water doesn´t run permanently. It has serveral parts:

• Catchment basin: Receives the rainfall water. The watershed makes everything go through the same canal.
• Drain: It presents different landforms:
• Pools or giant´s kettle: Areas where the water erosions creating this holes. The lower pressure makes the water move the little stone inside the pool making it deeper.

• Rafts: They are formed when there´s a bigger slope and the water has more energy thanks to this height difference.

• Waterfalls: water falling from an important height, formed when a river or stream flows over a precipice

• Alluvial fan: cone-shaped deposit where the water puts down the sediments when it loses its energy.

• Wild water: Watercourses but without a permanent basin. It produces different geological effects:

• Gullies: Waterfalls everywhere digging furrows on the slopes or badlands.

• Fairy chimneys are also formed here (badlands).

• Limestone pavement: Grooves formed on the rocks (limestone) by dissolution.

• Rivers: Permanent basin and continuous water flow. 

          Some important considerations are:

• Balance profile.  Rivers tend to have as much erosion as sedimentation all along their basin. They rarely get this balance profile because of the tectonic movements.

• Rivers erode backwards. Water removes material from the top of the river.

• Landforms:

• Waterfalls
• Bends: Curve structures of the rivers. They are formed by the collision of the water against a wall which starts eroding. Near internal wall, where the water has less energy there is sedimentation. That´s why the curves get bigger every time (middle course).

• Floodplains: When there is an inundation, the water leaves sediments on both sides of the river.

Desertic/Arid Mophological Systems

A Desertic MS is an area characterized by a lack of available water, and where the main geological agent is the wind.

The geological processes include:

• Thermal stress: sharp temperature changes (mainly daytime and night) provoke expansion and contraction of rocks and, eventualy, their rupture.

• Haloclasty: salt crystallization causes rocks to break up when saline solutions in cracks evaporate and salt crystal expand and increase pressure on the rock.

Other geological effects are:

• Desert varnish: thin film like a shiny coating formed in the surface of stones due to the action of bacteria

• Salt lakes: wide areas covered of salt due to evaporation.

Structures formed on the desert slopes:

• Tafoni: Hollows formed on the rock because of the permeability or the pressure difference.

• Tor: Enormous accumulations of rocks on slopes of dry areas.

Structures formed on the plain:

• Glacis: Sediments that come from the top of the slope. They connect with channels called uadis which are really dangerous during rainfall periods (they have a waterborne).

• Monadnock or Inselberg: Mount formed on the plain with a different composition. The materials are created in depth and they come out as a consequence of the tectonic movements.

• Depressed areas: Occurs due to sediments accumulation when the water evaporates. For instance, Sebka (salty lakes).

Windy geological processes

The relief forms in the desert can be created by two different processes, both due to the wind:

• Deflation: The windy takes the sloope material, lowering the relief.

• Abrasion: The wind lifts the materials throwing them against other materials “sanding them down”.

Types of deserts

The wind moves from the higher pressures to the lower ones, losing its energy gradually. Since the anticyclones stay always in the same area, this wind movements generates three different types of deserts:

• Hammada: Rocky desert. The wind has a lot of energy so it takes the lightest materials and leaving the heaviest ones.

• Reg: It´s a stony desert but it also has sand unlike the hammada.

• Erg: Sandy desert. When the wind loses its energy, it puts down all the materials that it had been dragging (lower pressure areas). 

Other desertic structures and effects:

• Yardangs: Structures formed when the materials have a different resistance to erosion (Thicker layers than others).

• Dunes: Hills of sand built by the wind so they have uniform and smooth layers. They can also be formed because of changes on the amount of sand.

• Desert pavements: When the wind blows, it takes the lightest materials producing the accumulation of the heaviest ones.

• Mushroom rock: The wind blows and drags the sand particles to a certain height, so there will be a stronger erosion on the higher part. Sometimes, the composition of the materials is different.

• Haze: A lot of sand on suspension that difficulties the sight, during strong windy periods (Canary Islands receive sand storms from Africa).

Periglacial Mophological Systems

A Periglacial MS is an area in the edge of a glacial system, formed also because of the effect of ice, but due to freezing and unfreezing processes (areas with temperatures ranging 0-10º)

The typical landscapes are:

• Patterned ground, formed by symmetrical geometric shapes of ground material

• Blockfields, or areas covered by large angular blocks.

• Permafrost:  soil at or below the freezing point of water 0 °C

• Padded grass: grass growing in a frozen area that increase its volume due to ice and looks like padded when unfreezing

Glacial Mophological Systems (Glaciers)

A Glacial MS (glacier) is a zone where a huge amount of snow is accumulated creating areas of permanet ice (areas of high lattitude or altitude). This accumulation flows down, draging sediments, to areas with higher temperature, where it melts.

There are different types:

• Alpine (mountain, valley) glacier: A glacier head (cirque) is formed in high altitude areas and the glacier flows downhill (like an ice river)

• Continental glacier (ice sheet): Large extensions of ice in high lattitude areas.

• Hanging glaciers: Similar to alpine glaciers but smaller, running at a different level and ending on a bigger one.

A mountain glacier has different parts:

• Cirque: wide place on the top where snow is accumulated

• Tongue: ice river that flows downhill

• Moraine: mass of rocks dragged by the ice in its way down the mountain. Moraines can be:
• Lateral. Formed on the sides of the glaciar.
• Rogen. Under the ice, in touch with the ground.
• Medial moraine. Union of lateral moraines in the confluence of two glaciers.
• End or terminal. It´s formed where the glacier melts 

Some geological effects associated to a glacier are:

• Crevasse: fracture zone in a glacier

• Serac: huge block or column of ice

The glacier shapes the land relief in several ways:

• Glacial erratic: piece of rock that differs from the size and type of rocks that are native to the area in which it rests

• Sheepback rock: result of the glacier erosion (abrasion) process

• Glacial till: piles of glacial deposits of different types

• Esker: Long, sinuous glacial deposits

• Drumlin: hill formed by the sediments draged by the glacial ice

• Tarn (ibón in the Pyrenees): lake formed in when the glacier finds a basin.

• Horn: mountain with a pyramidal shape eroded by different glaciers.

• Glacier valley: U-shaped valley with steep walls formed by glacial erosion.

• Hanging valleys: They are those that flow at a different height than the principal, and this one cut its walls.

• Fiord: glacier valley filled of sea water