By 65 million years ago, the end of the Cretaceous period and the beginning of the Cenozoic, the continents were aleady beginning to take on a more recognizable form. Flowering plants also continued to diversify during this period.

Cretaceous Period

In a roundabout way, the Cretaceous period got its name from the type of rock deposited along the northern shores of the Tethys Sea in a band running from what is now Ireland and Britain to the Middle East. The Latin for chalk is creta, so the period was named the Cretaceous.

25,000 years ago: a hamlet consisting of huts built of rocks and of mammoth bones is founded in what is now Dolní Věstonice in Moravia in the Czech Republic. This is the oldest human permanent settlement that has yet been found by archaeologists. 16,000–13,000 years ago: first human migration into North America.

Fluctuations in the amount of insolation (incoming solar radiation) are the most likely cause of large-scale changes in Earth’s climate during the Quaternary. In other words, variations in the intensity and timing of heat from the sun are the most likely cause of the glacial/interglacial cycles.

Three rapid increases in rise rates (“pulses”) are noted here so that the majority of the 100 meters of sea level rise occurred from 14,000 to approximately 8,000 years ago, or 90 meters in roughly 6,000 years.

Global sea level has been rising over the past century, and the rate has increased in recent decades. In 2014, global sea level was 2.6 inches above the 1993 average—the highest annual average in the satellite record (1993-present). Sea level continues to rise at a rate of about one-eighth of an inch per year.

The most recent period of cooling and glaciation began approximately 120,000 years ago. Significant ice sheets developed and persisted over much of Canada and northern Eurasia.

At least five major ice ages have occurred throughout Earth’s history: the earliest was over 2 billion years ago, and the most recent one began approximately 3 million years ago and continues today (yes, we live in an ice age!). Currently, we are in a warm interglacial that began about 11,000 years ago.

Global average sea level has risen by about 8 inches (about 21 cm) since 1900, with about 3 of those inches (about 7.5 cm) occurring since 1993.