Compléter Past ecosystemsVersion en ligne Complete this activity on past ecosystems. par Belinda Schirmer 1 rock ecosystems changes fauna data abundance observations environment Aboriginal art represents a record of human of the dating back as far as 40 , 000 years . The art depicts the flora and of the past and changes in their . Scientists can place these observations in context with scientific to form a more comprehensive picture of past and the that took place in them . 2 existence remains paleontological macroscopic impression living mineralised Geological evidence and evidence provide clues to past ecosystems . All things can leave a trace of their . Evidence may include clues such as fossils , moulds and casts , remains or whole . 3 iron model remnants effect geological order atmosphere isotope events record Geochemical remains include of organic molecules or ratios only associated with living things . Changes in the can leave traces in the rock , such as banded formations . The time scale is a scientific that represents past natural in and allows scientists to infer cause an . 4 change Antarctica gases oceans dust pattern traces accumulation core atmospheric climates Climate is defined as a long - term of ocean and conditions . Climate alters the chemical composition of and the atmosphere . The of ice layers in places such as leaves an annual record of and in the atmosphere at the time . These chemical can be retrieved in ice samples and analysed to help build a more complete record of past .