Geologic Record and Resolution

Climate Archive

A material that stores evidence of past climates

Climate Proxy

Indirect evidence used to estimate past climate conditions

Paleoclimate

The climate of Earth in the past

Biotic Proxy

Climate evidence from living things or fossils

Geologic Proxy

Climate evidence from rocks, minerals, or sediments

Geochemical Proxy

Climate evidence from chemical or isotope measurements

Geologic Record

Layers of rocks and sediments that preserve Earth's history

Fossil Record

Preserved remains or traces of past life

Incomplete Fossil Record

Not every organism or time period gets preserved

Why Fossils Are Missing

Organisms may decay, lack hard parts, or never get buried

Hard Parts and Fossils

Shells, bones, and teeth are more likely to be preserved

Sedimentation Rate

Speed at which sediment builds up

High Sedimentation Rate

Sediment builds up quickly and may preserve more detailed climate changes

Low Sedimentation Rate

Sediment builds up slowly and may miss short climate changes

Consistent Deposition

Sediment builds up regularly with fewer gaps

Inconsistent Deposition

Periods of deposition are interrupted by gaps or erosion

Temporal Resolution

How much detail about time a climate record preserves

High Resolution Record

Can show climate changes over short periods

Low Resolution Record

Shows broader changes over longer periods

Bioturbation

Organisms mix sediment and blur climate records

Erosion

Removal of sediment that can destroy part of the climate record

Compaction

Sediment is squeezed together and its thickness decreases

Bubnoff Unit

1 millimeter of sediment per 1000 years

Ice Core Archive

Old ice containing chemical signals, dust, and trapped gases

Ice Core Resolution

Can preserve seasonal or yearly climate changes

Tree Ring Archive

Annual growth rings that record environmental conditions

Tree Ring Thickness

Changes in growth that may reflect past environmental conditions

Speleothem

Cave deposit such as a stalagmite that records past climate

Speleothem Resolution

Depends partly on how quickly cave minerals grow

Coral Archive

Coral skeletons that can preserve seasonal climate information

Sedimentary Archive

Rock or sediment layers containing fossils and chemical evidenc