Role of Paleomagnetism in the Construction of Earth’s Geographic Past

Rocks have the ability to preserve magnetic information used in determining past geographic formations. The purpose of this report is to determine the past location of a site from a given data set’s magnetic information and the calculations found through their application to paleomagnetism. Magnetic information includes the rock sample’s location and concentration of trace magnetic particles which were used to find declination and inclination on site. The sample’s paleolatitude and paleolongitude are calculated using trigonometric equations that are derived using calculus. After a statistical analysis, these results are compared to the present day’s magnetic poles to determine the past location of the site. This location, along with the magnetic information, is combined to construct a past geographic formation that existed a billion years ago. This process reveals that the site currently found in southwest Namibia, was located near the coast of modern-day northwest Africa during the late Mesoproterozoic Era within a 95% certainty. When compared to past literature these results show the reliability and role of paleomagnetism, as well as the importance of collaboration across the geosciences.

After the boring billion and before the freezing millions: evolutionary patterns and innovations in the Tonian Period

The Tonian Period (ca. 1000–720 Ma) follows the ‘boring billion' in the Mesoproterozoic Era and precedes ‘snowball Earth' glaciations in the Cryogenian Period. It represents a critical transition in Earth history. Geochemical data indicate that the Tonian Period may have witnessed a significant increase in atmospheric pO2 levels and a major transition from predominantly sulfidic to ferruginous mid-depth seawaters. Molecular clock estimates suggest that early animals may have diverged in the Tonian Period, raising the intriguing possibility of coupled environmental changes and evolutionary innovations. The co-evolution of life and its environment during the Tonian Period can be tested against the fossil record by examining diversity trends in the Proterozoic and evolutionary innovations in the Tonian. Compilations of Proterozoic microfossils and macrofossils apparently support a Tonian increase in global taxonomic diversity and morphological range relative to the Mesoproterozoic Era, although this is not reflected in assemblage-level diversity patterns. The fossil record suggests that major eukaryote groups (including Opisthokonta, Amoebozoa, Plantae, and SAR) may have diverged and important evolutionary innovations (e.g. multicellularity and cell differentiation in several groups, eukaryovory, eukaryote biomineralization, and heterocystous cyanobacteria) may have arisen by the Tonian Period, but thus far no convincing animal fossils have been found in the Tonian. Tonian paleontology is still in its nascent stage, and it offers many opportunities to explore Earth-life evolution in this critical geological period.