Download SoilPaintingTemplates - Montana Soil and Water Conservation Society

Cenozoic
Pre-Belt
Mesozoic
Pre-Cambrian
Paleozoic
Cambrian and
Ordovician
Page 1
from http://mbmg.mtech.edu/gmr/00-old/gmr-montanageology.asp#time
Geologic time, from the formation of the Earth
at ~4.6 billion years ago to the present, is
understood and represented by layered rocks
throughout the world. By understanding the
relative ages of layered and cross-cutting rocks,
and the fossils they contain, geologists have
developed a geologic time scale. Relative ages
are cross-correlated with numerical ages derived
from radioactive isotopes of elements contained
in some of the geologic units. Using fossils and
radiometric ages, geologists can compare the
geologic strata of Montana with the "type
section" of Devonian rocks exposed in the Devon
area of southern England.
For example, using fossils, geologists can
compare certain geologic strata in Montana with
the "type section" of Devonian age rocks in
Devon, England and determine that their ages
are the same. Radiometric dates tell us that
Devonian rocks fall in a range of 369–410 million
years ago.
Page 2
Topsoil: The top layer of
soil that consists of organic
matter,
minerals
from
decomposing rocks, and it
provides nutrients and
habitat for bacteria, fungi,
insects, arachnids, plants,
and small animals.
Subsoil: In northern and
eastern
MT,
it
is
predominantly Glacial Till,
which is a heterogeneous
mixture of sand, silt and
clay. It is found between the
topsoil and the bedrock.
Bedrock: In places, it is
weathered at the top, and
becomes
increasingly
consolidated with greater
depth. In many places of
western MT, it is exposed at
the ground surface, with
little to no topsoil above it.
Page 1 of 3
Montana Salinity Control Association
www.montanasalinity.com
Saline Seep FORMATION
Rechar
Area
ge
Discharge
Area
FORMATION: Saline seeps form when ground water brings
salts from the soil up to the surface. When the topsoil is
bare of plants in the recharge area, precipitation percolates
through the soil profile, collecting salts along the way. It
builds up the ground water table, and when the ground
water gets close to the surface, a saline seep forms in the
discharge area. Plants can’t grow where there is too much
salt on the soil surface.
RECLAMATION: To reclaim saline seeps, perennial forage (like
alfalfa) is planted in the recharge area, which is uphill from
the seep. This prevents the extra water from building up
underground, and the salts go back down to where they
don’t harm plants on the surface.
Topsoil: The top layer of soil that
provides nutrients for plants to live
in.
Saline Seep RECLAMATION
Perennial Forage
Subsoil: In northern MT, it is
predominantly Glacial Till, which is
a heterogeneous mixture of sand,
silt and clay. It is found between the
topsoil and the bedrock.
Bedrock: The bedrock is the
impermeable layer that the water
table builds up on, and it is the
source of salt that is found
throughout the soil profile.
Salt-Tolerant
Forage
Lowered Water Table
Montana Salinity Control Association
Page 2 of 3
www.montanasalinity.com
Saline Seep FORMATION
Bedrock Subsoil
Topsoi
l
Recharge
Area
Discharge
Area
Page 3 of 3
Montana Salinity Control Association
www.montanasalinity.com
Bedrock Subsoil
Topsoi
l
Saline Seep RECLAMATION
Perennia
Forage
l
Lowered Water
Table
Salt-Tolerant
Forage