Introduction
Early Cretaceous
Mid-Cretaceous
Late Cretaceous
Palaeontological
Evidence
Sedimentological
Evidence
Isotope Evidence
Summary
Glossary
Further Reading
Climate Change Home Page
KT Event Links
Back to
Bristol Palaeontology
Homepage
Introduction
The stratigraphic record (rocks and fossils) harbours the evidence of the Earth's changing climates. Climate can be read from this record in many ways:
Palaeontology - from the assemblages of
fossil
plants and animals. Climatic zones are indicated by floral (plants) and faunal
(animal) distribution.
Sedimentology - from the nature of the
sediments. For example, the present
distribution of these sediments, their mineralogy, the varied facies represented,
features that indicate the agencies of transport and deposition, and the soils
that represent former land surfaces.
Isotope Geology - can determine past
surface and ocean temperatures from studies of terrestrial and marine sediments and polar
ice cores. The ice cores can only be used for study of relatively recent
climate.
Factors affecting climate
The following factors have to be considered when attempting to assess the climate in the geological past:- geography - the arrangement of continents and oceans influence ocean circulation and planetary albedo.
- ocean circulation - the warmer year-round temperatures at high latitudes in the Mid Cretaceous could be partly explained by the poleward transfer of heat through the ocean.
- atmospheric composition - such as the concentration of CO2, the major greenhouse trace gas.
This evidence indicates certain climatic factors, such as rainfall, land and ocean temperatures, and the effects of variations in these. More indirect evidence comes from meteorology, geophysics and astronomy.
Climate variation across the globe
Global climate is comprised of a number of local climates. The regional and local change in climate is reflected by the systematic decline of diversity of plants and animals with increasing latitude and altitude. This decline in diversity can be mainly attributed to the fall in temperature and in the case of latitude, due to a lower incidence of sunlight with increasing latitude.Today, climate varies considerably from the equator to the poles. Was the climate in the Late Cretaceous as geographically variable?
Climate change through time
The reconstructed climates at specific times and locations can be compared to determine the variation in climate through time. The rate of change can also be determined.During the majority of the Late Cretaceous, climate change was thought to be gradual. However, the boundary with the next time period, the Tertiary, witnessed a catastophic event (the KT event). This instantaneous event is thought to have led to the extinction of the dinosaurs and many other forms of life. What does the evidence in the geological record tell us about the climate change in the Late Cretaceous up to and including this boundary?
Surf this website into the geological past when dinosaurs roamed the planet. What was the climate in the Late Cretaceous and how did it change?
| Intro | Early Cretaceous | Mid-Cretaceous | Late Cretaceous |
| Palaeontological Evidence | Sedimentological Evidence | Isotope Evidence |
| Summary | Glossary | Further Reading | Climate Change Home Page | KT Event Links | Back to Bristol Palaeontology Homepage |