·       Drylands have ____ geomorphic characteristics, e.g., the Sahara is mostly ______, whereas the SW USA has lots of ____ and very little sand.

(a)  

Under the UN Aridity Index (____), an arid landscape is characterised by less than ____mm of mean annual precipitation and an inter-annual variability of __-___%.

(a)  

1.     Subtropical high pressure ____ cause aridity because drylands are found underneath the ____ limb of the ____ cell, causing warm air and high pressure with little rain).

(a)  

There may also be ______ effects to create aridity, where many things are happening at once. For example, Southern Africa – it is under high pressure (tropic of ____) and the cold ____ ocean current, continentality from the ____ ocean monsoon which goes from east (where all the rain is dropped) to west (which is therefore very dry).

(a)  

In the early 20th century, as American research on drylands emerged, which kind of approach dominated the discipline?

(a)  

    In the mid 20^th century, the use of ____ photographs and _____ images enabled us to see the interiors of deserts and showed for the first time that aeolian landforms were ____. This generated interest into the diversity and efficiency of ____ processes in deserts.

(a)  

·       Only (a)   % of the world’s drylands are covered by aeolian sands!

·       Transverse dunes = found in areas with (a)   /narrow wind regime.

·       Linear dunes = form in areas of __/multi directional wind regimes. The dunes are _____ forms as the ridges get longer in the resulting direction of the wind.

·       Livingstone (1993) did work on how these dunes form. The dune moves from left to right (not really up and down) like a _____.

(a)  

·       Star dunes = formed in areas of _____ wind regimes, they’re ______ forms and grow upwards.

(a)  

·       The suspended load of dryland rivers is _- (a)   x that of perennial rivers.

·       Channels are commonly (a)   due to the supply of coarse particles, erodible banks and variable discharge.

Which authors wrote a paper and graph in 2002 demonstrating how wind and water work together in deserts?

(a)  

Perceptions of the desert are often (a)   because of the "othering" of the desert and its people.

Deserts are viewed as barren and desolate because they are viewed through a (a)   lens.

___ of all people live in drylands, making it the single most populous ____ on the planet.

(a)  

The _______ impact of rain drops dislodges _____, creating a _____ and ____ process.

(a)  

Drylands are (a)   environments, meaning that we must confront our own biases about them.

“‘Desert’, ‘arid zone’, ‘dryland’ and sometimes other terms such as ‘_____’ are all used somewhat interchangeably and ______ in both popular and scientific literature. This can lead to confusion regarding differences in levels of moisture availability from place to place". (Thomas, 2011)

(a)  

·       “While Africa and Asia each contain almost a ____ of the global arid zone, inspection of Figure 1.2 clearly shows that Australia is the most arid continent, with approximately ___% of the land area being arid or semi-arid.” (Thomas, 2011).

(a)  

·       “Arid and semi-arid land covers almost one-third of the land surface of the globe. Almost 60 per cent of it is true desert. The remainder varies from _____ _____ to _____ _____.”

Smithson, P. et al. (2008).

(a)  

In the early 20th century, _____ weathering processes - especially ____ weathering - were thought to dominate drylands

(a)  

As well as thermal cracking, insolation weathering has been linked to _____ of the outer layers of boulders and the ______ ______ of rocks comprised of minerals with different thermal properties.”

(a)  

Which weathering process can shape and polish rocks?

(a)  

·       “Desert weathering is _____, selective and frequently _____(Cooke et al., 1993).”

(a)  

·       Desert varnish (alternatively rock varnish), as it is termed, is composed of ____ minerals, oxides and hydroxides of ____ and/or iron, together with detrital particles, which form a layer...... It probably takes many ____ of years for a characteristic black to brown desert varnish to develop, apparently through the action of bacteria which preferentially ____ and concentrate certain elements (especially manganese) supplied from dust and surface water.”

(a)  

Thermal contraction crack polygons are “a network of ____ fractures resulting from thermal stresses in frozen ground (Harris et al. 1988), not necessarily associated with ____-____ cycling, unlike sorted polygons.”

(a)  

·       “This analysis suggests that polygon troughs represent an additional ____ path for water in the McMurdo Dry Valleys hydrological systems..... extends the time and space during which ____ and _____ reactions can occur…” - Levy, J.S., Head, J.W. and Marchant, D.R., 2008.

(a)  

·       “We suggest that the ____ effect of large numbers of ____ cycles of compression and decompression due to east-west–oriented heating and cooling cycles on the rock surface preferentially favors surface cracks in a ____-____ direction.” McFadden et al, 2005.

(a)  

·       Previously, it was thought that “deserts represented ____, and highly ____ weathering environments”. (Viles and Goudie, 2000).

(a)  

Fruitcose lichens' dominant effect is to protect the underlying surface from erosion. ____lichens, on the other hand may be dominantly ____ or _______ ____ weathering, depending largely on the nature of the underlying rock type and their growth and decay characteristics. (Viles and Goudie, 2000).

(a)  

·       Alluvial fans = _____ landforms whose surface forms a segment of a ____ that radiates downslope from the point where the stream leaves the source area. Alluvial fans are widespread, especially in arid, mountainous and periglacial areas, but are especially notable in particular ____ environments where there is a marked contrast between mountain front and depositional area. ____ creates mountainous areas that provide debris and increased stream competence. (Thomas, 2016).

(a)  

·       Playas = ____ ____ which originate from the surrounding mountains and drain into ____.

(a)  

On the Cabo de Gata east-coast fans, high ____ ____ caused ____ erosion and fan profile foreshortening, leading to distally induced incision of the fan channel (Harvey, 2002).

(a)  

“When wind velocity exceeds the ____ velocity required to initiate sand grain movement (generally this is about 20 km h−1 ), the grains begin to roll along the ground, but after a short distance this gives rise to a bounding or jumping action called ____ (Goudie, 2013).

(a)  

·       Erosivity = describes the ability of a fluid to ____.

·       Erodibility = the _____ of a material to erosion.

(a)  

·       Entrainment = the process of sediment being ____ ___.

(a)  

·       Grain entrainment gets the sediment ____the fluid so that they can be _____away.

(a)  

·       Fluid threshold = threshold ____ ____ above which the resisting forces of the grains are exceeded, therefore ____ and entrainment can occur.

(a)  

“The nature and ____ of geomorphology leads many practitioners to focus on particular landforms and/or landforming processes. This _____ approach leads to a division of the discipline into apparently discrete units of study such as fluvial, glacial, aeolian, coastal and so forth (Sherman 1999). (Bullard and Livingstone, 2002).

(a)  

“Williams (1994) has noted that as a generalisation, _____ landscapes in deserts tend to be significantly older than the _____ landforms they possess: in other words, very ancient events have set the scene in which modern deserts have evolved." (Arid Zone Geomorphology).

(a)  

“Following the ____ ___ ____ there is near continuous evidence of dune-building" in the southwestern Kalahari (Telfer and Thomas, 2007).

(a)