Biological weathering is the breakdown of rocks through the action of living organisms like plants, animals, and microbes. It occurs as roots penetrate rocks to absorb water and nutrients, thereby exerting pressure that cracks rocks apart over time. Microbes and lichen also contribute through chemical reactions, secreting acids or chelating compounds that dissolve rock minerals. While the forces are small, continual effects from a wide variety of organisms gradually cause mechanical and chemical weathering of surface rocks.

1. EZHILMATHI. S
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2. Biological
weathering is the
weakening and
subsequent
disintegration of rock
by plants, animals
and microbes

3. Organic weathering
It is the disintegration of
rocks as a result of the
action by living organisms
Plant and animals have a
significant effect on the
rocks as they penetrate or
burrow into the soil

4. Biological weathering can work with physical weathering,
for example root exert pressure which helps to weakening
rocks
It can also produce chemical weathering, for example where
microorganisms produce organic acids which help to
dissolve minerals
Microscopic organisms can produce organic chemicals that
can contribute to the rock’s mineral weathering

5. The roots penetrate into the soil in search of
nutrients and water
They go through cracks or joints in the rocks and as
they grow they progressively crack the rock apart
They also emit organic acids that aid to dissolve the
rock’s minerals
Although the process is physical, the pressure is
exerted by a biological process

7. Algae, moss, lichens and bacteria break down rock
minerals by altering the rock’s chemical composition
Lichen is fungi and algae living together in a
symbiotic relationship
Fungi release chemicals that break down rock
minerals; the minerals thus released from rock
consumed by algae

9. These compounds can break down iron and aluminum
minerals in the rocks
They release acidifying molecules and chelating compounds
The amount of biological activity that breaks down
minerals depends on how much life is in that area
They arise out of bio-chemical reactions
They also bring about moist chemical micro-environments

10. This can move rock fragments to the surface
Moles, squirrels and rabbits can speed up the development
of fissures
Piddock shells drill into rocks for protection by releasing
acids to dissolve the rocks
There are many small animals that eat away the rock’s
minerals and bore hole so as live inside it

12. This equally dig, crash, and widen the
cracks and wind up fragmenting the
rocks apart
These activities include mining, road
construction, and housing developments

14. Historically, scientists have studied weathering as an abiotic
process.
In the mid 1980’s, scientists studying geothermal sediments
from Yellowstone found the some of the first evidence of
biological weathering when they discovered iron-silicate
minerals in association with bacterial remains.
The first application that included biological weathering in
LAPSUS was Temme and Veldkamp’s study in South Africa.
The original implementation of biological weathering was
developed by Minasny and McBratney, 2006.

15. Biological weathering and the long-term carbon
cycle: integrating mycorrhizal evolution and
function into the current paradigm
Crystalline nanotube-forming bacteria help
crumble mountains in a tropical rainforest

17. http://www.eartheclipse.com
Das, Dilip kumar/ 1996/ introductory soil science
http://www.thelonelyspore.com

18. Thank u