This first chapter shows rocks on the large scale, how they
adorn the earth's surface in mountains, cliffs, plains and valleys.
They look as if they are timeless and everlasting, but they are, in
fact, transient, as ephemeral as everything in life. Mountains and
valleys come about by action and movement, tectonic uplift and
persistent erosion. Today's mountain chains arose from yesterday's oceans and plains. Over tens of millions of years these
mountains will wear down, to become plains or to be swept
over by oceans once again. Earth has always been and will
always remain a dynamic system, moving to and fro between
creation and destruction, order and chaos.
The geomorphology seen here, from a
well-known viewpoint in Death Valley, California, is called 'badland erosion' and is a typical erosive pattern for deposits of
shale, rhyolite or other soft sediments in arid regions, where
rain only comes in occasional downpours.
Iceland is where one becomes
aware of the making of new land, of new mountains, rocks and
minerals; as close to creation as can be. Landmannalaugar, in the
southern interior of Iceland, is an area of active volcanism. The
striking landscape of elongated, sharply crested hills and Vshaped valleys, is formed by rapid erosion of the soft, rhyolitic
lava's that were recently deposited here. Rhyolite is a characteristic type of extrusive rock, formed from shallow magma
(molten crust) and rich in silica, aluminum, potash and feldspar. It
has subdued, earthy colors, fluctuating from green to yellowbeige and brick red. A recent outpouring of obsidian, a glassy
and fluid variety of lava, can be seen meandering across the rhyolite hills like a black snake.A brief classification of rock types is
presented in the next chapter.
Nowhere the phenomenon called erosion
is more spectacularly typified than by the bizarre, pinkish brown
pinnacles and spires of Bryce Canyon National Park, USA.
Frost and thaw impart striking
features to the bedded limestone that makes up the southern
face of Der Hohe Dachstein, the godfather of the Dachstein
Massif in the northern Alps of Austria.
This would-be lunar landscape is
the North Cainesville Mesa, east of Capitol Reef Park in Utah,
U.S.A. The flat-topped mountain in the background, Factory
Butte, is an exemplary butte, also referred to as a mesa. The
ridges showing an escarpment on one side and a gentler slope
on the other side are called cuestas. The crude and edgy geomorphology exhibited here is indicative of the recent, tectonic
movements that are still going on in this area.
Pounded upon relentlessly by mammoth Atlantic waves, the Cliffs of Moher, in western Ireland,
remain unperturbed in their dark and menacing steepness, thinly veiled by a diaphanous haze of seawater spray.
Awe-inspiring is the natural scenery of the
Vesteralen, an island group off the coast of northern Norway.
The mountains here may stand out in crystal-clear light one
moment, to become dark and looming within the briefest spell
of time, shrouded in clouds.
Black tuff or tuffstone, formed by the
accumulation of ashes and coarser particles from volcanic outbursts, characterizes much of the landscape in South Eastern
Iceland. The narrow, winding Fjardara Canyon has been cut in
these sediments by a small river. In summertime the crystal
clear stream, fringed by colorful vegetation, vies with the steep
black canyon walls and strange pinnacles to make this place the
setting of an uncanny fairy tale.
This unique desert of glistening
gypsum sand, surrounded by dark mountain ranges, is located in
southern New Mexico, USA. Wandering into this blinding
expanse of rolling dunes is a mesmerizing experience. There is
no more than a lone yucca stalk or other lean shrub to remind
one of being on planet Earth.
Shiprock is a striking landmark in northwestern
New Mexico, USA, protruding 500 meters up out of the surrounding flat plains. Shiprock is a volcanic neck, the central
basaltic cone that remained after the softer slopes and sediments surrounding the ancient volcano disappeared by erosion.
Several dykes of the same basaltic rock, one of which is seen in
the picture, fan out from the central cone into the surrounding
plains. That form has inspired the native inhabitants of this
region, the Navajo Indians, to give this rock the much more
telling name Tse Bidahi, meaning 'Winged Rock'.
10
adorn the earth's surface in mountains, cliffs, plains and valleys.
They look as if they are timeless and everlasting, but they are, in
fact, transient, as ephemeral as everything in life. Mountains and
valleys come about by action and movement, tectonic uplift and
persistent erosion. Today's mountain chains arose from yesterday's oceans and plains. Over tens of millions of years these
mountains will wear down, to become plains or to be swept
over by oceans once again. Earth has always been and will
always remain a dynamic system, moving to and fro between
creation and destruction, order and chaos.
The geomorphology seen here, from a
well-known viewpoint in Death Valley, California, is called 'badland erosion' and is a typical erosive pattern for deposits of
shale, rhyolite or other soft sediments in arid regions, where
rain only comes in occasional downpours.
Iceland is where one becomes
aware of the making of new land, of new mountains, rocks and
minerals; as close to creation as can be. Landmannalaugar, in the
southern interior of Iceland, is an area of active volcanism. The
striking landscape of elongated, sharply crested hills and Vshaped valleys, is formed by rapid erosion of the soft, rhyolitic
lava's that were recently deposited here. Rhyolite is a characteristic type of extrusive rock, formed from shallow magma
(molten crust) and rich in silica, aluminum, potash and feldspar. It
has subdued, earthy colors, fluctuating from green to yellowbeige and brick red. A recent outpouring of obsidian, a glassy
and fluid variety of lava, can be seen meandering across the rhyolite hills like a black snake.A brief classification of rock types is
presented in the next chapter.
Nowhere the phenomenon called erosion
is more spectacularly typified than by the bizarre, pinkish brown
pinnacles and spires of Bryce Canyon National Park, USA.
Frost and thaw impart striking
features to the bedded limestone that makes up the southern
face of Der Hohe Dachstein, the godfather of the Dachstein
Massif in the northern Alps of Austria.
This would-be lunar landscape is
the North Cainesville Mesa, east of Capitol Reef Park in Utah,
U.S.A. The flat-topped mountain in the background, Factory
Butte, is an exemplary butte, also referred to as a mesa. The
ridges showing an escarpment on one side and a gentler slope
on the other side are called cuestas. The crude and edgy geomorphology exhibited here is indicative of the recent, tectonic
movements that are still going on in this area.
Pounded upon relentlessly by mammoth Atlantic waves, the Cliffs of Moher, in western Ireland,
remain unperturbed in their dark and menacing steepness, thinly veiled by a diaphanous haze of seawater spray.
Awe-inspiring is the natural scenery of the
Vesteralen, an island group off the coast of northern Norway.
The mountains here may stand out in crystal-clear light one
moment, to become dark and looming within the briefest spell
of time, shrouded in clouds.
Black tuff or tuffstone, formed by the
accumulation of ashes and coarser particles from volcanic outbursts, characterizes much of the landscape in South Eastern
Iceland. The narrow, winding Fjardara Canyon has been cut in
these sediments by a small river. In summertime the crystal
clear stream, fringed by colorful vegetation, vies with the steep
black canyon walls and strange pinnacles to make this place the
setting of an uncanny fairy tale.
This unique desert of glistening
gypsum sand, surrounded by dark mountain ranges, is located in
southern New Mexico, USA. Wandering into this blinding
expanse of rolling dunes is a mesmerizing experience. There is
no more than a lone yucca stalk or other lean shrub to remind
one of being on planet Earth.
Shiprock is a striking landmark in northwestern
New Mexico, USA, protruding 500 meters up out of the surrounding flat plains. Shiprock is a volcanic neck, the central
basaltic cone that remained after the softer slopes and sediments surrounding the ancient volcano disappeared by erosion.
Several dykes of the same basaltic rock, one of which is seen in
the picture, fan out from the central cone into the surrounding
plains. That form has inspired the native inhabitants of this
region, the Navajo Indians, to give this rock the much more
telling name Tse Bidahi, meaning 'Winged Rock'.
10