Palynologists have many tables by which they compare the particles seen under the microscope. It resembles the definition of minerals. Only here the main thing is not color, but the shape of the grains. Pollen and spores resemble microscopic rounded crystals. Sometimes they have air sacs, sometimes they are like a propeller. If we take into account that the sizes of dust particles are hundredths and thousandths of a millimeter, then their long, almost round-the-world trips are not surprising. True, the pollen of some plants (larch, for example) is not very stable and poorly preserved in a fossil state. This, of course, reduces the possibilities of analysis. The ability of pollen to large migrations complicates the reconstruction of a natural stop: the pollen found in the sample could belong to plants located tens or hundreds of kilometers from these places. Individual dust particles can enter the sample randomly. In addition, it is important to know not only which plants lived here at the time the layer was deposited, but also to distinguish among them the dominant and rare ones. For this, the amount of spores and pollen in each plant species is counted. If, for example, the sample contains fifty percent of the pollen of spruce and thirty percent of the pollen of meadow plants, in these places spruce forests once grew among meadows.

Of course, there are many difficulties and uncertainties in the pollen spore method. However, to clarify the nature of the interglacial, he gives irreplaceable materials. Large plant debris, animal bones, and stone tools of humans are relatively rare. And pollen and spores are present in almost all layers. Only in glacial deposits, and in well-washed river sands, there are few of them. Spore-pollen analysis has become especially widespread in our country. One of the first was investigated for spores and pollen famous Likhvin outcrop. A palynological analysis confirmed that the climate during the Likhvin interglacial was somewhat warmer than modern. In the Kaluga region, then, judging by the fossil pollen, broad-leaved forests grew, with an abundance of hornbeam. There were many coniferous trees: spruce, fir. They lived here evergreen yew, walnuts, Euryal water lilies and Brazil, and some other plants that have survived from more ancient, Tertiary times. Such plants, unusual for modern landscapes, as part of the flora are called exotics. Palynological analysis allows you to determine the relative age of the rock layers. The more pollen of exotics, the usually the older layer. The more pollen of modern plants, the younger the layer.