History Of The Biosphere Flashcards
What is the process called in which microbes make rock?
Biomineralisation
What are microbial Mats?
Biogeochemical cycles
Slimy biofilm of aerobic, photosynthesising Cyanobacteria on mud surfaces (autotrophs)
Sub-surface anaerobic heterotroph layer derives food from Cyanobacteria above
What are stromatolites?
Limestone layered rock structures Thought to be ancient microbial mats Most ancient fossils known Microbes live on surface Sediment is deposited on the microbes Microbes grow through the sediment and form new layer
What played a part in the development of an oxygenated atmosphere?
Cyanobacteria - photosynthesising microbes that generated gaseous oxygen
Banded iron formations - ferric-iron rich rocks - first oxidised sediments
Eukaryotic algae - including ‘sea weeds’ and found as fossils 2.1 bya
Red beds - terrestrial oxidised sediments - free oxygen in high concentrations in air for first time
What are banded iron formations caused by?
Made 2.5 to 1.8 bya
Early atmosphere had no free oxygen
High percentage of iron in crustal rocks
Released due to weathering, ends up as iron ions in Ocean
Blue/green bacteria produce O2 as waste product
O2 reacts with iron to form iron oxide (magnetite)
Once all iron has reacted O2 levels build up and polluted environments kill of bacteria (producing the silica layers)
Cycle continued for nearly 1 billion years
When was the first colonisation of the continents?
1-0.7 bya
Rise of fungi
Colonisation of the continents by lichens
Increased phosphorus nutrient release due to biotic weathering of rocks
Closely likened to increase in nitrogen availability
Major step change in biological productivity
What happened 750-580 mya?
Neoproterozoic glaciations Snowball earth Rise in atmospheric oxygen Fall in atmospheric CO2 Coincides with origins of complex multicellular soft bodied animals
What is the Cambrian explosion?
Evolutionary radiation - rapid acceleration of appearance of new species in eukaryotes
All major groups formed
Advent of shells on body (fossils)
When were the major mass extinctions?
429 mya 364 mya End Permian mass extinction 204 mya End Cretaceous mass extinction
What is the anthropocene epoch?
Proposed new geological epoch
Human activity significant enough to leave a widespread geological record
Global impacts on - soil, atmospheric composition, biodiversity, trace elements and isotopes
What are microbes?
Single celled organisms including bacteria, some fungi and algae and Protozoa
