|
|
|
|
|
| Graph showing percentages of biogenic silica in two Lake Baikal cores. Since diatoms and algae are the most important microorganisms in the lake, biogenic silica is a measure of primary productivity. tadiocarbon ages in years are shown by arrows. First-order changes are caused by glacial (blue)-interglacial (red) cycles, with transitions shown in purple. Second-order fluctuations, such as the peak at 3,770 years, are due to shorter climatic events. |
 |