Earth & Environmental Sciences
stromatolite
100%
Proterozoic
70%
microfossil
56%
Archean
51%
basin
40%
chert
38%
craton
37%
acritarch
35%
Mars
35%
Precambrian
33%
fossil
31%
thermal spring
28%
stratigraphy
27%
carbonate
22%
microbial mat
19%
cyanobacterium
18%
biomarker
18%
biostratigraphy
16%
sedimentology
14%
hydrothermal alteration
14%
national park
14%
microstructure
14%
sediment
13%
history
13%
paleontology
12%
iron
11%
Raman spectroscopy
11%
glaciation
11%
sulfate
11%
trace fossil
11%
sinter
11%
sulfur isotope
11%
rock
10%
dolomite
10%
creek
10%
hopanoid
10%
mineral
10%
sulfide
10%
bacterium
10%
sandstone
9%
carbon isotope
9%
biofacies
9%
organic matter
9%
organism
9%
early Earth
9%
carbon
8%
microorganism
8%
paleobiology
8%
paleoenvironment
8%
geological record
8%
Chemistry
Carbonate
33%
Organic Matter
21%
Environment
19%
Geochemistry
15%
Kerogen
15%
Sedimentation
13%
Bitumen
11%
Biological Marker
9%
Soil
8%
Ore Deposit
8%
Mineral
7%
Sulfate
7%
Carbon Atom
7%
Isotope
6%
Pharmacological Metabolism
6%
Gammacerane
6%
Clay Mineral
6%
Salinity
6%
Raman Spectroscopy
6%
Hydrocarbon
6%
Sulfide
5%
Biogeochemistry
5%
Calcite
5%
Quartz
5%
Environmental Process
5%
Cholestane
5%
Organic Carbon
5%
Stable Isotope
5%
Crystalline Texture
5%
Physics & Astronomy
mars
34%
minerals
16%
fossils
15%
Mars exploration
11%
meteorological parameters
11%
geochemistry
11%
deposits
9%
cratons
9%
rivers
8%
exobiology
8%
sediments
8%
radon
7%
signatures
6%
eukaryotes
6%
telescopes
6%
geology
6%
carbonates
6%
United Kingdom
6%
spindles
5%
infrared telescopes
5%
histories
5%
derivation
5%
analogs
5%
biosphere
5%
genes
5%