Alūksne Upland (Alūksne Highland; ) is a hilly area of higher elevation in eastern

Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...

, in the historical region of

Vidzeme Vidzeme (; Old Latvian orthography: ''Widda-semme'', ) is one of the Historical Latvian Lands. The capital of Latvia, Riga, is situated in the southwestern part of the region. Literally meaning "the Middle Land", it is situated in north-centra ...

. Sometimes it is referred to as the East Vidzeme Upland, to distinguish it from another hilly area of Vidzeme, Vidzeme Upland, also known as the "Central Vidzeme Upland".

Geography

The upland continues into the neighbouring Estonia as the

Haanja Upland Haanja Upland (also Haanja Highland, ) is a hilly area of higher elevation in southern Estonia.drainage divide A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a single ...

between

Gauja The Gauja River (, ) is a river in the Vidzeme region of Latvia. It is the only large river of Latvia that begins and ends its flow in Latvia. Its length is 460 km, of which 93.5 km (approximately one-fifth) are in Gauja National P ...

and

Daugava The Daugava ( ), also known as the Western Dvina or the Väina River, is a large river rising in the Valdai Hills of Russia that flows through Belarus and Latvia into the Gulf of Riga of the Baltic Sea. The Daugava rises close to the source of ...

river basins.

Geology and geomorphology

The Alūksne Upland forms an "isometric insular" glacial upland that originated as a

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...

-cored

plateau In geology and physical geography, a plateau (; ; : plateaus or plateaux), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. ...

when converging ice lobes stalled and deposited

till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

. Its summit plateau ranges from 190 to 230 m a.s.l., rising 20–40 m above adjacent lowlands, and is mantled by 6–8 m (locally up to 28.5 m) of

glaciolacustrine Sediments deposited into lakes that have come from glaciers are called glaciolacustrine deposits. In some European geological traditions, the term limnoglacial is used. These lakes include ice margin lakes or other types formed from glacial erosio ...

clays and

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

s laid down in ice-dammed lakes during the final stages of the Weichselian deglaciation.

Climate

The Alūksne Upland has a humid

continental climate Continental climates often have a significant annual variation in temperature (warm to hot summers and cold winters). They tend to occur in central and eastern parts of the three northern-tier continents (North America, Europe, and Asia), typi ...

characterised by cool summers and cold winters. According to long-term records from the nearby Alūksne meteorological station (1922–2003), mean annual

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

is about 728 mm, with roughly 242 mm falling from June to August and 143 mm from December to February. Over 1950–2003, annual precipitation at Alūksne showed a modest but statistically significant upward trend. Regional temperature data from Rīga–University (1795–2002) show that mean winter temperatures have risen by approximately 1.9 °C and mean annual temperatures by 1.0 °C, with spring means up by 1.3 °C. Winters have thus become shorter and milder, contributing to a reduction in

ice cover Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice ...

duration on upland streams by several days per decade and to higher winter discharge, especially during positive phases of the North Atlantic oscillation.

References

{{DEFAULTSORT:Aluksne Upland Hills of Latvia Plateaus of Latvia