Ice layer dating
In part, they measure the age of rocks and other natural materials by dating techniques.
They can date rocks by gauging the amount of decay of radioactive elements.
The time necessary for half of any given amount of one element (the “parent element”) to decay to become another element (the “daughter element”) is called the element’s “half-life.” Ice cores, for example, contain data about Earth’s past climate.
Geologists use a dating technique called K-Ar geochronology to find the age of layers of volcanic ash in ice cores. By measuring the ratio of K to Ar in feldspar crystals in volcanic ash, geologists can determine the time of the eruption and, thus, the age of ice in which the ash is found. Heating causes the kernels to begin popping, thereby starting your simulated “radioactive decay clock” and producing popped “daughter” popcorns.
Overall, the climate was much colder and drier than it is today.
Since most of the water on Earth's surface was ice, there was little precipitation and rainfall was about half of what it is today.
Scientists have debated for years over the cause of the extinction, with both of the major hypotheses — human overhunting and climate change — insufficient to account for the mega die-off.
Recent research suggests that an extraterrestrial object, possibly a comet, about 3 miles wide, may have exploded over southern Canada, nearly wiping out an ancient Stone Age culture as well as megafauna like mastodons and mammoths.
They had become extinct at the end of the Cretaceous Period, more than 60 million years before the Pleistocene Epoch began.During peak periods with most of the water frozen, global average temperatures were 5 to 10 degrees C (9 to 18 degrees F) below today’s temperature norms. The variation in temperatures produced glacial advances, because the cooler summers didn’t completely melt the snow.While evolved, many vertebrates, especially large mammals, succumbed to the harsh climate conditions of this period.Birds flourished during this period, including members of the duck, geese, hawk and eagle families.There were also some flightless birds such as ostriches, rheas and moas.