Sentences with phrase «glaciations began»

Subsequently, large Northern Hemisphere glaciations began to occur when pCO2 dropped below about 300 ppm in the middle Pliocene.

To think we understand a lot about of Ice Ages when we can only guess whether the next glaciation begins in 20K or 50K years seems self - contradictory on the face of it.

And finally our current Quaternary glaciation began a brief 2.58 mya.

The most recent period of cooling and glaciation began approximately 120,000 years ago.

Not exact matches

While the first of the glaciations that the team studied was probably triggered by nonvascular plants such as mosses and liverworts, the second ice age — the one that began around 445 million years ago — may have been brought on by the rise and spread of vascular plants.

The late Proterozoic — the time period beginning less than a billion years ago following this remarkable chapter of sustained low levels of oxygen — was strikingly different, marked by extreme climatic events manifest in global - scale glaciation, indications of at least intervals of modern - like oxygen abundances, and the emergence and diversification of the earliest animals.

The first Ediacaran to begin crawling around would have discovered a world devoid of predatory animals, with a seafloor covered either in thick bacterial mats or toxic sediment and, possibly, a climate thawing from a worldwide glaciation event known as «Snowball Earth.»

New insights into the glaciation cycles that occurred on Earth long before humans began affecting the temperature of the atmosphere and oceans are now possible using the technique of measuring noble gas quantities.

Current interpretation of Y - chromosome and mtDNA data suggests that modern - day Portuguese trace a significant amount of these lineages to the paleolithic peoples who began settling the European continent between the end of the last glaciation around 45,000 years ago.

Glaciation in Alaska's Chugach Range began 5 million years ago with glacial advance and retreat that has shaped the dramatic landscape.

In the preface to his book on «Climatic History and the Future» H.H. Lamb says: «Recent research...... has rendered more specific the expectation that the beginnings of the next glaciation will be upon our descendants within 3000 to 7000 years.

The «Ice Age» that is sometimes discussed as in our near future is actually just another glaciation in the current ice age which began some 2 or 3 million years ago and is onging.

However as illustrated in Figure 1, initiation of Antarctic glaciation happened 35 million years ago, more than 30 millions years before Arctic glaciation ever began.

The three lines are: (1) the beginning: the Khirthar transgression and the onset of neritic carbonate accumulation in the Bartonian Age (preceding onset of the Middle Eocene climatic optimum [MECO]-RRB-; (2) the midlife change (Bartonian - Priabonian transition): the shift from carbonate - rich to carbonate - poor, higher - nutrient environments under estuarine circulation, causing widespread dysaerobia culminating in opaline silicas; and (3) the Eocene - Oligocene = Priabonian - Rupelian boundary and glaciation during oxygen isotope event Oi - 1, with return of improved ventilation in neritic environments and resumption of carbonate accumulation.

Seems to me — Ray will I hope correct me if I» m wrong — that what MacDonald is describing may be well known; temperatures peaked at the end of the last glaciation and began a long slow decline, typical pattern.

On longer time scales, sediment cores show that the cycles of glacials and interglacials are part of a deepening phase within a prolonged ice age that began with the glaciation of Antarctica approximately 40 million years ago.

The Northern Hemisphere glaciation, which began 3.2 million years ago, was driven by tectonic events, such as the closing of the Panama seaway and the uplift of the Andes, the Tibetan Plateau, and western parts of North America.