The Nördlinger Ries Crater leaflet

8/13/2019 The Nrdlinger Ries Crater leaflet

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The Nrdlinger Ries Crater

The Nrdlinger Ries Crater is situated in the

south of Germany in the Bavaria state and the

centre is about 6km northeast of Nrdlinger

city as can be seen in the image to the right.

The impact was of a 1.5km diameter asteroid

travelling at about 72,000 km/h which

happened about 14.314.5 million years ago.

The asteroid penetrated 1km into earths

crust. It is a complex crater and the outer ringhas a 25km diameter and the inner crater is

12km in diameter. The impact energy is

thought to be roughly equal to the energy of

1.8 million Hiroshima bombs which is 2.41021

joules

History and Information

For over 100 years, until 1960 when Eugene

Shoemaker showed that the formation wascaused by a meteorite impact, it was assumed

that the Ries depression was caused by

volcanic activity. There are six pieces of

evidence that can be found to prove that a

formation was created by an impact and not

by a volcanic event and there are as follows:

Shatter cones these are cone shapedstructures found in the rock beneath

impact craters, the apex (point) of thecone is at the top. A pressure of 2 30

Giga Pascals is needed to create these.

Only meteorite impacts and underground

nuclear explosions can create these

features.

Multiple planar deformation features microscopic features in grains of silicate

materials such as quartz or feldspar that

are caused by a shock wave from the

impact. They are narrow planes of glassy

material in

This image shows part of the southern rim of the

crater, sloping down to the flat basin on the right hand

side.

Nrdlinger Nrdlinger Ries Crater

An aerial photograph showing the scale of the

structure and how it looks from above.


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Interesting fact

The two major rock

formations that make up

part of the ejecta of the

crater, the suevite and Bunte

breccia were used as training

ground for some of the

Apollo astronauts.

parallel sets that have distinct orientation

with respect to the crystal structure of the

grain.

High pressure mineral polymorphs thehigh pressures caused by impacts can form

high pressure polymorphs of various

minerals such as quartz, titanium dioxide

and carbon. Quartz can become either

coesite or stishovite and carbon can

become diamond.

Morphometric structuressize, shape andmorphology of the structure.

Pseudotachylytes and breccias -Pseudotachylytes are fine grained glassy

fault rocks that are made up of a very fine

grained matrix that occur in veins. Breccia

is rock that is made of fragments of

minerals or rock held together by a fine

grained matrix. They contain

contamination of extraterrestrial material

such asiridium andosmium anomalies

Impact melt sheets, dikes and meltbrecciasA dike is a sheet of rock that has

formed in a crack in pre-existing rock. Inimpacts molten rock caused by the event

goes into cracks in pre-existing rock and

crystallizes. Melt breccias is similar to

breccia apart from the matrix that holds

the fragments together. In melt breccia the

cementing breccia is made from

crystallized impact melt.

Two types of titanium dioxide high pressure

polymorphs were found at the Nrdlinger Ries

crater. Shocked quartz was also found at the

Nrdlinger Ries crater, shocked quartz is only

found at impact sites and not volcanic

formations therefore when it was discovered

at Nrdlinger Ries by Eugene Shoemaker it

was proof that this was the result of animpact not volcanic activity. There is impact

breccia at the site composed of granite and

gneiss along with shatter cones.

Computer simulations indicate that the

meteor would have been about 1.5 km in

diameter and hit the surface at an angle of 30

50 degrees and came in from a west-

southwest to east-northeast direction. The

area that it hit was composed of about 500 800m thick sedimentary rock with granite and

gneiss underneath.

There is another crater 42 km west-southwest

from the Nrdlinger Ries crater called the

Steinheim crater which is the same age and it

is likely that they were created at the same

time by a binary asteroid. The Steinheim

crater is much smaller and was created by an

object approximately ten times smaller thanthe one that created Nrdlinger Ries.

This image shows some of the impact

breccia at the Nrdlinger Ries crater; it is

from just outside of the craters inner ring.For a sense of scale the hammer in the

ima e is 35cm lon
http://en.wikipedia.org/wiki/Iridium_anomalyhttp://en.wikipedia.org/wiki/Osmiumhttp://en.wikipedia.org/wiki/Osmiumhttp://en.wikipedia.org/wiki/Iridium_anomaly


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Formation

The crater is a complex crater as can be seen

in the diagram below which shows a cross

sectional view of the crater. It has a central

uplift in the middle of a shallow, flat crater

floor which is surrounded by the inner ring,

megablock zone and the outer crater rim.

Central uplifts are made of one or more rings

with a peak in the middle and they are

composed of rock that has been brought up

from great depth. The inner crater basin has

been filled in with deposits of suevite, then

after the impact lake deposits filled the crater

in further. The inner ring is made up of shock

metamorphosed material that has been

overturned and upturned by the impact.

Megablocks are large blocks of rock that were

displaced when the crater formed. It is still

not known for certain how megablocks are

formed but there are two leading theories.

The first is that during the crater excavation

stage they were thrown out and deposited at

the same time as the ejecta blanket. The

other theory is that during the modification

stage they slumped inwards.

Complex crater formation can be broken

down into stages. The first of these is contact

with the surface and compression of the rock.

A supersonic shock wave is created at the

point of contact which goes through the

impactor and the surface it has

hit. This shockwave compresses

the impactor and the target and

as a result the target undergoes

shock related changes such as

transforming the quartz mineral in

the rock into shocked quartz and

it melts the impactor. Next

excavation takes places as the

crater grows and material is

ejected out, in the Nrdlinger Ries

impact about 150 km3

of rock was

thrown out and it fell in the area surrounding

the crater up to 40 km away. Near the crater

the debris was up to 200m thick. The crater

that is created is unstable so modificationtakes place, during this stage the walls of the

crater collapse under gravity and the rim

collapses inwards and the centre is uplifted.

The central uplift is a result of material

attempting to return to a state of gravitational

equilibrium. This process is shown in the

image above.

This is a cross sectional diagram of the crater showing the structure of

the crater and where different types of rock can be found.

An image depicting complex crater

formation.


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Interesting fact

Many buildings in the town of

Nrdlinger are made out of

stone quarried from the crater.

The stone contains millions of

tiny diamonds smaller than 0.2

mm in size, so many buildings in

Nrdlinger have diamonds in

their stone.

Museum

In the city of Nrdlinger

there is a museum about

the crater called the Ries

Crater Museum. It has

numerous exhibits on

meteorites, rocks and

fossils but the main

exhibition is about the

Nrdlinger Ries crater and

its formation. The museums

location, opening times and

admission fees are asfollows:

Address

Ries Crater Museum,

Eugene - Shoemaker - Platz

1, 86720 Nrdlingen

Opening times

Tuesday to Sunday - 10 amto 12 am, 1.30 pm to 4.30

pm

Monday - closed; public

holiday regulations on

request

Admission Prices

Adults 4

School student 1.50

University Students 2

Disabled 2.30

Senior 3

Family ticket 8.50

Group Adults 3 each

At the museum there is a piece of Moon rock that

weighs 165g that was brought back in the Apollo 16

mission. It is from the Descartes region of the southern

lunar highlands.

There is also an exhibition about the origin of the

Chicxulub crater in Mexico in the Yucatan Peninsula and

the extinction of the dinosaurs at the museum. As part

of the exhibition there is a short film.

Documents

The Nördlinger Ries Crater leaflet