Geography - Coal mining in the
Goitzsche/ The geology of the Goitzsche
Members
of the project
Andreas Bunge
Anja Köppe
René Hilbig
Janine Körner
The historical development of the
Goitzsche
The open-cast mine “Goitzsche” is situated in
Saxony-Anhalt and Saxony, in the area between Bitterfeld and Delitzsch.
Its total area amounts to 62 km2 two thirds of which are
in Saxony-Anhalt, and one third in Saxony. Coming from Bitterfeld (in the
direction of Wittenberg) you can reach it following the B 100. The adjoining
villages and towns include Bitterfeld, Muldenstein, Friedersdorf, Muehlbeck,
Pouch, Loebnitz, Sausedlitz, Laue, Petersroda and Holzweißig.
In 1949 the development of the open-cast mine
”Goitzsche” started south-east of Bitterfeld. Within the 40 years of mining
317 million tons of brown coal were extracted. To do so about 850 million
tons of overburden had to be moved.
In 1955 amber was discovered in the Bitterfeld
mine. But mining only started in 1975 after the geological analysis. Until
1990 about 408 tons of precious minerals were extracted. After that the
extraction was stopped because of financial reasons. Moor oaks of an age
between 4000 and 6000 years were found, too.
After stopping coal-mining in 1991 the redevelopment
of the area of 60 km_ began in order to create an urban recreation area.
After flooding this area will form a lake district with about 400 million
m2 of water, 25 km2 water area and a shore line of
66 km.
In 1997 the construction of the flooding equipment
for the former open-cast mine “Goitzsche” began. It consists of the
dikes, the connecting pipelines and the actual flooding canal in Muehlbeck.
All this serves to conduct water from the “Mulde River” to the former mining
area. After the completion of this equipment the test flooding started
on 6th July 1999. At that time 1 m3 of water per second was
flowing into the former mining area.
On 7th May 1999 the “real” flooding began.
Since then about 3 m3 per second (depending on the water level
of the Mulde River) are conducted into the former mining area of Muehlbeck
and from there on to the former mining area of Niemegk to fill it with
“nice” water of the Mulde River.
On 6th June 1999 the building of the sea-level
tower “Pegelturm” started directly at the flooding canal. The upper part
of the “Pegelturm”was placed on its base on 16th March 2000. You can reach
the tower via a swimming 220-metre-long pontoon bridge, which will rise
its level in the process of flooding.
On 13th April 2000 the lakeside promenade on
the edge of the “Goitzsche” was opened to the public. The way leading from
the outskirts of Bitterfeld to the “Pegelturm” is even illuminated at night.
On 28th July 2000 the flooding of the former
mining area Roesa was begun with the help of a pipeline and a pumping
station.
2. |
Development
of coal-mining in the Bitterfeld area until 1900 |
-
1804
The first attempt to mine the coal of Bitterfeld.
It failed because the ground-water level couldn`t be kept under control.
-
1834
development of the Royal Mine at the “Farm House”
-
1838
beginning of test excavations
-
1839
opening up of the mine “Auguste”
-
1842
mine “Wilhelm” in Hohenlubast mentioned for the
first time
-
1842
foundation of mine “Richard” in Sandersdorf
-
1843
opening up this mine
-
1844
abandonment of the Royal Mine at the “Farm House”
-
1845
development of the mine “Moehring”
-
1845
development of the mine “Johannes” (No 6) near
Wolfen
-
1846
opening up of this mine
-
1846
development of mine No 9 near Grossmoehlau
-
1847
foundation of the “German Mine” near Zscherndorf
-
1848
opening up of the mine “Adelheid”
-
1850
mine No 79 comes into operation near Greppin
-
1852
foundation of mine “vergissmeinicht” (No 291)
near Zscherndorf
-
1855
development of the mine “Maria-Theresia”
-
1856
foundation of the mine “Ausdauer”
-
1858
foundation of the mine “Gemeinsinn” in Delitzsch
-
1859
the most important mines in the Bitterfeld area
name
extracted coal
workers
mines No 64,222,297
419,197 t (all in all)
95 (all in all)
mine “Johannes”
269,975 t
50
mine “Richard”
137,554 t
39
mine “Auguste”
141,729 t
41
In the Bitterfeld mines locomotives were used
for excavation. Railroad wagons were pushed near the open-cast mine and
then pulled by horses up to the real working place. In 1849 steam
engines were introduced in the “German Mine”. In 1857 the brown coal-mines
were connected to the railway network.
In the two years of crisis 1858 and 1859 the
output per worker sank.
1857: 356.8 t
1860: 346.8 t
1861: 494.1 t
Some mines were closed because of free competition
since they were not profitable due to their unfavourable position e.g.
in the vast forest areas of the Duebener Heath.
In 1864 the amount of coal was increased as the
table shows:
(diagram
amounting of raw coal 1864)
Name
Amount of coal in tons
“German Mine”
492,230
mine “Auguste”
467,587
mine No 79 (near Greppin)
409,880
mine No 314 (near Muldenstein)
275,999
mine “Johannes”
234,301
mine “Ausdauer”
127,074
mine “Richard”
123,778
mine “Vergissmeinicht”
109,501
In Bitterfeld the following property situations
had formed:
Private Mines
1. mine “Auguste”
2. mine “Richard”
3. “German Mine”
4. mine “Vergissmeinicht”
5. mine „Lutherslinde“
Mines owned by banks
1. mine “Johannes”
2. mine “Maria-Theresia”
Mines dominated by industrial capital
1. mine “Ausdauer”
Communal Mines
1. mine “Gemeinsinn”
2. mine „Maria Theresia“
Thus banks and industrial capital brought 30 %
of the coal- mines under their control.
At that time more workers were employed. Hence
a miner`s capacity increased like this:
1843
273 t
100%
1860
346 t
126 %
1870
518 t
189 %
A daily shift lasted 16 hours. In 1840 a worker
earned 25 “Silbergroschen” (silver coins) per “Kubik-Lachter” of raw coal.
A shaft worker earned two, a pit foreman three Talers.
In 1869 there were eight brown coal-mining companies
with 660 workers. There was an output of 6,900 447 Zentner of raw brown
coal (1 Zentner = 50 kg) worth 209,505 Taler.
6,380 628 Zentner worth 195,674 Taler were sold.
The average value per Zentner amounted to 0,92 Silbergroschen per Zentner.
Thus one worker produced 10,455 Zentner. Besides 16 steam engines (323
PS) were used.
In 18 74 ten brown coal factories employing 1,189
workers existed. There was an output of 13,687 381 Zentner of raw brown
coal worth 521,551 Taler. 13,687 045 Zentner were sold for a price of 502,963
Taler. The average value per Zentner amounted to 1,14 Silbergroschen per
Zentner. Thus one worker produced 11,512 Zentner. Factories used 23 steam
engines (421 PS).
Property situation at the end of these years:
Communal Mines
mine “Maria Theresia”
Private Mines
1. mine “Auguste”
2. mine “Richard”
3. “German Mine”
4. mine “Vergissmeinicht”
5. mine “Marie”
6. mine “Hermine”
Mines owned by banks and industries
1. mine “Antonie”
2. mine “ Luise” Corp.
3. mine “ Ausdauer” Corp.
4. mine “Gemeinsinn” Corp.
5. “Greppin Factories Corporation”
Then a crisis which set in in 1873 began to show
its effects on the output per person.
Year/output per person(diagramm
output per person)
1872/516,6 t
1873/ 642,4 t
1874/593,0 t
1875/560,2 t
1876/529,9 t
1877/628,2 t
1878/677,6 t
The production of brown coal briquettes started
at the end of the 1870s, at the beginning of the 1880s. This led to an
upswing of the briquette industry. The extraordinary competitions caused
a decrease of the coal prices between 1879 and 1884 from 13.7 down to 12.5
Pfennigs per hl. Because of the production of briquettes the district of
bitterfeld could become more competitive. This positive trend again led
to the following new establishments:
-
1888
development ot the mine “Friedrich 3rd”
-
1888
development of the mine “Golpa”
-
1891
opening up of the brown coal company in Petersroda
-
1897
foundation of the mine “Erich” in Sandersdorf
-
1898
-
1899
development of the mine “Karl Friedrich 2nd”
-
1895
the mine “Marie” (a new open-cast mine), because
mine “Klara X” had to be closed temporarily because of flooding
Property situation at the end of 1900
At the end of the 19th century banks already
own 50% of the mines.
Private Mines
1. mine “Auguste”
2. mine “Richard”
3. “German Mine”
4. mine “Vergissmeinicht”
5. mine „Marie“
6. mine „Ferdinand 3rd“
7. mine „Antonie“
Mines controlled by banks and industries
1. mine “Luise” inc.
2. mine « Ausdauer » inc.
3. mine „Erich“
4. mine „ferdinand 1st/2nd“
5. „Greppin Mines“ corp.
6. mine „Hermine“
By the introduction of machines (excavators) the
output of a miner rose up as follows:
1870 |
518 t |
100% |
1880 |
580 t |
112% |
1890 |
554 t |
107% |
1900 |
1010 t |
194% |
On 14th April in 1883 the first monopoly union
was formed in Bitterfeld. This union of the mines “Luise”, “Richard”, “Hermine”
and the “German Mine” was called “Union of Bitterfeld Industrials”. In
the course of 20 years the exploitation of one worker increased by 50 per
cent. In 1863 a worker produced 436 t, and in 1885 - 655 t of coal.
Amount of raw coal |
1889 |
1895 |
1899 |
Mine "Deutsche Grube" |
253.869 t |
304.638 t |
388.845 t |
Mine Luise |
229.928 t |
329.364 t |
398.066 t |
Mine Auguste |
187.154 t |
211.657 t |
279.927 t |
Mine Hermine |
197.717 t |
173.462 t |
261.734 t |
Mine No 6 (near by Wolfen) |
132.434 t |
155.203 t |
220.440 t |
Mine Antonie |
127.080 t |
137.018 t |
137.343 t |
Mine Marie |
99.771 t |
* |
158.417 t |
3. |
The
history of the Goitzsche |
-
1830
infertile land planted with pine trees
-
1908
pening up of the mines ”Leopold” and “Theodor”
-
1908-1961
open-cast mine Holzweissig uses electric railway
engines
-
1911
the Siemens-Schuckert-Company receives the license
to search for coal in the “Goitzsche”
-
1915
mechanisation of open-cast mining with the help
of an electric spoon excavator
-
1917
first attempts with mechanical movement of the
overlay shelf
-
1921-1928
open-cast mine Paupitzsch/Petersroda
-
1929
Bitterfeld bought the front part of the “Goitzsche”
-
1947
first plans for opening the “Goitzsche”
-
1949
opening of the “Goitzsche”
-
1951
open-cast mining in the “Goitzsche”
opening up of the open-cast mine in Muldenstein
-
1951-1991
the “Goitzsche” opened up by a spoon excavator
-
April 1953
courses of Rivers Leine and Lober shifted to
prevent flooding the mining areas
-
1953-1955
the railway route Bitterfeld-Berlin was
rebuilt north
-
1956
destruction of the village Zoeckeritz
-
1956-1961
railway route Leipzig-Berlin and the B 184 rebuilt
west
-
50s
recultivation of slagheaps
-
1961
beginning of regular reforestation mostly with
poplars and oak-trees
-
1961
opening up of the open-cast mine Holzweissig-west
-
1966-1975
transfer of the Mulde River bed by 9.2 km
-
1972
closing down the open-cast Muldenstein
-
1976
flooding that cast
-
1976
creation of the Muldewater Reservoir
-
1976
the village “Paupitzsch” destroyed
-
1978
village Niemegk destroyed
-
1980
closing down the open-cast mine Holzweissig-West
-
Sept. 1984-June 1985
longest transfer of huge mining equipment from
open-cast mine of Leipzig to the Goitzsche
-
1984
courses of Rivers Lober and Leine changed once
again
-
1984-1991
open-cast mine Roesa
-
1989
temporary establishment of three nature reserves
-
1990
forest area opened for relaxation
-
1990
another change of River Mulde and destruction
of five villages prevented, although mining had been planned up to 2040
-
15th May 1991
redevelopment, flattening, stabilization of slopes,
recultivation and removement of mining equipment started
-
1998
beginning of flooding - “Bitterfeld Sea”
4. |
The
geology of the Goitzsche |
The earth layers of the Goitzche
The earth layer profile of the Goitzsche consists of main- and
countless smaller layers.
The origin time as well as the substances which the smaller layers
consist of is not precisely to be determined.So we confine ourselves to
the most imporant six layer sorts and want to explain in simple but in
geologically correct ways.The most frequent layer,which the geologists
also call terrace gravel,consists mainly of gravel sand.It came into being
in the Pleistocene period 125.000-6000.000 years ago.This geological period
is devided again into different periods whereas
the development of gravel sand belongs to both the Elster cold
spell and to the Saale cold spell.The thickness of this layer can amount
up to 8 metres.
The second layer,which has to be considered,has also came into being
in the Pleistocene period and is called clay ("B‰nderton").This clay layer
is the smallest one of the 6 layers because it has only a thickness of
a few centimetres.In exceptional cases such a layer can be up to two metres
thick.
The third layer is called Beckenschluff.It came into being in the pleistocene
period,too.It's thickness can't be stated exactly,because the "Schluff"
is usually in or between the clay layers and has different thicknesses.
Another layer in the Goitzsche is the gravel layer.It also came into
being in the Pleistocene period.It can also be found in or between different
layers.But general gravel layers have also been found.These layers have
an average thickness of 6-7 metres.
The fifth layer is called "Geschiebemergel"and came into being in the
Pleistocene period through alluvail deposits caused melted snow.The
thickness of this layer can be about 13 metres.
For the area of Bitterfeld the last and most important layer is the
brown coal layer.It is called stratum.These strata came into being in the
Tertiary period,strictly speaking in the upper oligocene.The Bitterfeld
strata have a thickness of about 19.70 metres.Above the compact coal layer
are carbonaceous clay and sand layers which can have a thickness of about
4 metres.
Comment of geological terms
geology: sciene of structure and the development of the earth
earth layers
-
sand: -loose rock with a size of grain of 0.06 up to 2.00 mm
-
clay: -mixture of different mineral particles with a size of grain
< 2 .....m
-
"Schluff" -loose rock in the size of grain between 0.063 and 0.002
mm
-
"Geschiebemergel": -through melting glaciers deposited, unlayered
mixture of clayey calcareous ingridients and rock (picus/drift)
-
stratum :-layerly sediments of useful mineral
Present geological era
Concluding table (table)
What is amber?
As amber you call compact fossile tree resin of pine wood from the early
and middle Tertiary period.Its age can be up to 100 million years.The amber
of Bitterfeld belongs to the period between lower and upper miocene.It
is nearly 25 million years old.
Amber is a mixture of carbon,hydrogen and oxygen.The collecting formula
for amber is (C10 H16 O).
The development of amber
Amber is an ancient yellow-brown tree resin of extincted pine wood of
the Tertiary period.In this time of the geology the resin dripped from
the trees onto the forest soil and hardened after 30 to 40 million years
to the valuable amber.
Kinds
1. succinite group - succinite, Gedanit, Goitschit
2. Glessit group - Glessit, Bitterfeldit, Purglessit
3. Beckerit group - Beckerit
4. Stanit group - Stantienit, Pseudostandienit
Amber is divided into different groups.The Succinit-,die Glessit-,die
Beckerit und die Stanit group.
These groups are divided into different kinds depending on the groups
as you can see above.
Amber extraction in Bitterfeld
The reason for extraction was the lack of amber in the VEB "Ostseeschmuck"(jewellery)
in Ribnitz-Damgarten in the 1970s.The supply from Russia decreased from
10t to 1t per year.Because of newspaper advertisments Bitterfeld's miners
sent amber to Rignitz-Damgarten in 1974.The frequency of contributions
caused the VEB "Ostseeschmuck"(jewellery) to give Leipzig geologists the
order for a fest mining in Bitterfeld.
Utilization of amber
sort 1 |
40% share |
taleer then 46 mm |
sort 2 |
13% share |
20-46 mm |
sort 3 |
50% share |
7-20 mm |
sort 4 |
33% share |
3-7 mm |
All sorts were sold to the VEB Ostseeschmuck.
The amber mined in Bitterfeld was divided into 4 sorts.All sorts were
sold to the VEB "Ostseeschmuck"(jewellery) in Ribnitz-Damgarten.
The sorts 1 to 3 were manufactured jewellery in Ribnitz-Damgarten.
The 4th sort was delivered both to the state-owned enterprise "Ostseeschmuck"
(jewellery) and to the state-owned company DELICIA Delitzsch.In Delitzsch
the amber was made into either amber oil or colophony rosin.But this brought
only little success that's why the 4th sort was made into pressed and liquely....melted
amber.
How was amber mined?
Before 1975 amber was still mined by hand.But since 1975 this had been
changed.They began with the manual mining of amber on the opencast mining
floor,with prospecting hoe and shovel.
From 1976 till 1990 the mechanical production of amber with scoops,dumbers
and wet processing plant began in the mining fields Niemegk and Friedersdorf/Mühlbeck.
In 1991 the extraction of amber began in the wet production with a
dredger in the mining field Friedersdorf/Mühlbeck.
On 31st March 1993 the amber mining was discontinued.
Mining figures(Chart:
amounting of amber)
1975 -mining of amber by hand
-later pilot system for mining
6. |
Assembly
of an opencast mining |
To explain the assembly of an opencast mining you must know
that there is more than the far visible hole.
As one of the first work the mining field must be examined and surveyed
geologically.This work is partly done by the mark aparation.Then you must
try to grips with the ground water.For that you mostly take filter wells
which are integrated into so-called edge bolt pipes in modern opencast
minings.At the same time you must to start with the clearing of the surface.That
includes the deforestation of extant forests,the move of streets,overhead
lines of electro energy, rivers, streames and so on.
When this has happened, you can start removing the top soil, the upper
cover bed.Usually you use smaller bucket wheels or proceedig dredgers for
that.This humus soil is normally used for the recultivation of extant dumps
of other opencast minings or you sell them to other prospective buyers.The
transport of these masses was usually done by train in the area of Bitterfeld.
As a next step the rest of the covers layer was to clear away now.This
material was either put into other opencast mining rest holes to recultivate
them or it was deposited to a high dump which you can also call outside
dump.An example is the hill of Bitterfeld.But if materials, which you could
use otherwise, were in these layers of the earth, this was also done.Usefull
gravel and sand were delivered to the building industry, for example,or
clay was made available for the brickyards.For the task to clear away these
covering layer you used bucket chain dredgers in the high or deep cut.
In the Goitzsche were these were the DI 000 and the DI 200.The removed
material was also transported by trains.In some opencast minings you also
used so-called tram systems for this.The levels of grade on which the big
gadgets were located were also called banks.If there was enough exposed
of the "Black Gold",its mining could be started.In the Goitzsche you used
a bucket wheel dredger SRs250 and for the deep and bucket chain dedgers
D800.The coal was also transported by trains from the opencast mining.
To guarantee this train operation,appropriate ramps had to be piled
up at the turning point of the opencast minings,because the trains could
only overcome a certain gradient.If you got enough off-coaled area,you
could start to let the overburden fall into the same opencast mining.The
tipping out of the dead material is also called falling and is managed
by a depositer.This overburden.....
was also transported to the depositer by train operation in opencast
minings.Thus the trains went in semicircle.They were loaded at the dredgers,went
to the dpositer,tipped out the rocks into so-called ditches went back to
the dredger empty again.This was also called train play.
In opencast mines in which conveyor belts were dominating the dead
rocks also came per conveyor belt installation to the depositer, which
was regulated by conveyor belt collecting point.
The opencast mine moved slowly because on the one side rock was extracted
and on the other side material was tipped out again.You can also say "the
opencast mine was wandering". If you extract more from one end,this end
will mover faster.Therefore the opencast mine circles.Thus the other end
is also called turning point.
Instead of using train or conveyor belt transport it's possible to
go the shortest way across the opencast mine if the opencast mine develops
parallely. For that you employ overburden conveyor equipment like in the
opencast mine Delitzsch South-West. The disadvantage of this technology
is that only one limited area of coal stratum can be exposed according
to span of the overburden conveyor equipment. This disadvantage is especially
obvious at damages or disturbance of big appliance, because you cannot
go on working as with other forms of extraction with different excavators.
Not only for this reason we are endeavour to hold the maltunction as
small as possible.That's why the maintenance was highly developed and on
every big appliance therwas an engineer to settle small repairs on the
spot.
To realize the progressing of the opencast mine the railways and conveyor
belts installations had to be removed.Conveyor belt installations are usually
moved by bulldozers according to miner's style. There are special moving
engines for the railway system. The big appliance on track vehicles always
had relevant equipment with them.Of course that is not necessary on big
appliance and catopillar vehicle.
(2nd version)
The opencast mine is an extraction of useable minerals and rocks, whose
natural bed is uncovered or is only covered by relatively thin top layer.
The top soil is taken away to unlock the opencast mine. The overburden
ist stored on a dump outside the opencast mine. During the extraction of
mineral in the uncovered part the extraction of overburden goes on, so
that the extraction can spread to the sides. If a sfficiently big opencast
mine has developed by extraction the continuing overburden can be stored
in the opencast mine itself. By this method you can say that the
opencast mine moves. Overburdens and minerals are usually extracted terraced
whereas the height of the banks depends on the engines used.The opencast
mine can be up to 500m deep.
The transportation of the overburdens to the dumps takes place by large-capacity
vehicle which are pulled by locomotive on rails or by conveyor belt over
an conveyor belt equipment. Instead of railway systems stope belt systems
can be used as well.
In the centre of opencast mine you can find the conveyor belt street,
which transports coal. At so-called conveyor belt collection points the
coal is exposed by sloping conveyor belt systems from the opencast mine
and then it is loaded on alternative transportation vehicles (large capacity
vehicle, lorry) and transported to the consumers (briquette factory,power
station). Under particular geographic conditions this can also be realized
by conveyor belt systems (if a power station is near the coal-mine).
7.
|
The
geology of the brown coal |
The brown coal was mainly formed during two epochs of earth
history, namely pit coal in the Carbon and brown coal in the Tertiary period.
During the time of the brown coal we can distinguish between 5 different
sections. Only two of them have economic importance: the older Eocene and
the younger Oligocene and Miocene brown coal. When the older brown coal
was formed the today's Northern Germany was covered by a sea. Later its
extension increased.In our district the eastern border ran from Delitzsch
via Roitzsch, Ramsin, Thalheim and Reuden to Dessau. The Eocene climate,
about 50 million years ago, was warm, almost tropical. The flora consists
of e.g. palms, dates, bayleaf- and cinamon trees. By lowering land and
rising ground-water level the flora and fauna was destroyed. The extendind
sea above deposited sand and mud on the destroyed flora and fauna. In the
following Oligocene time the sea came from the north overflooding large
parts of Germany. In the middle of Oligocene the sea border ran south of
Halle and Leipzig. It disappeared and advanced once again in the later
Oligocene.The southern border was situated near Aken, Dessau, Kemberg
and Schmiedeberg.The fine deposits like sand, gravel and clay reached a
thickness of up to 20 metres.The numerous findings like shells, shark teeth,
fishbones a.s.o. proof the fact that these are really sea deposits. The
end of Oligocene was about 20 to 25 million years ago. During that
time the brown coal of the area of Bitterfeld was formed. As we have already
said the sea border ran near Dessau-Schmiedeberg. The brown coal forest,
which existed in our area, was limited in the west by Brehna, Renneritz,Ramsin,
Jeßnitz, Raguhn. The border on the other side of the district was
formed today's Mulde river between Krina, Rösa to Gossa and turned
towards the heath. Between Schköna and Lutherstein was a forest reaching
to Tornau and Schwemsal in today's Düben Heath.In the meantime
the temperature of the climate decreased and became warm and mild.Because
of this the tropical flora disappeared.Conifers and deciduous trees of
the temperate climate zone appeared now. The forest mainly consisted of
e.g. giant pines, marsh cypresses, alders, maple-trees, poplars and ferns.
In the clays depositing above the brown coal leaves of different
trees of the former forest of our native country have been well preserved.
In a rare case a pine cone survived millions of years. Sometimes the wood
silicified. These pieces are special concrete evidence of the composition
of the former forest. You can see such single proofs in the museum. In
the past it was assumed that forests forming brown coal had been swamp
areas. The present proved the contrary because the giant red woods don't
grow in permanently wet or swamp areas. The formation of peat and swamp
areas required dryness. This would also supply an explanation for annother
fact: Air roots of subtropical plants couldn't be found in the brown
coal although having been searched for eagerly. However we can't be absolutely
sure that there were no water plants in these forests at all.
Because of the lowering land and the rising ground-water level the plant
formation began to die slowly. After that, new plants started growing.
If there was no lowering land, the fate of the swampland was sealed. The
ground-water level rose too fast and transformed the whole place into a
lake. The water, which is now flowing above the swampland, covered it slowly
with sand and clay. These sea deposits protected parts of the former swampland
from decomposition and level down. By this protection the complicated chemical
change could start, which is now known as carbonization.Plant material
lying in the sea transformed into coal by a kind of hindered burning. The
oxygen in the plants was consumed and the carbon was enriched.Results of
research from other brown-coal areas showed that to form a one-meter layer
of brown coal more than 3000 years were needed. But for Bitterfeld this
number only counts approximately. Furthermore the brown coal layers in
the district of Bitterfeld generally lie tectonically undisturbed and horizontal.
On the contrary, the disturbance by the Ice Age, particularely in the "Dübener
Heide" is more important.
The snow water of the glaciers with its whirls has eroded several large
parts of strata. On their surfaces the whirl holes can still be seen.Recently,
a bigger disturbance of that kind has been noticed in the opencast
mine "Goitzsche". By the pressure-effects of the ice parts the layers were
compressed or mixed with sand and clay. This especially happened in the
area of the "Gniest" and the "Hohen Gieg" in the "Dübener Heide".
The coal deposits in the area of the knee of the Mulde river in Bitterfeld
had been eroded and washed away. The river bed of the Mulde poured out
from Düben to Bitterfeld and here it turned north to Dessau.In the
large curve of the river near Bitterfeld the glacier valley had eroded
the sand and the clay lying above the coals and washed away the coal
bed.
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