Layers of cross-bedded sand can be indicative of a DESERT environment wind is responsible for the formation of these sedimentary structures. Sand dunes preserved in rocks can be quite large. These structures form as a result of the migration of dunes due to the action of the wind. Dunes are not often preserved but a few can be observed in thick sandstone units.
It is always done on purpose.
<span>The nucleolus is the structure within the nucleus of eukaryotic cells. It consists of RNA, DNA, and proteins. The nucleolus is involved in ribosome biogenesis which results in the synthesis of ribosomes. Ribosomal RNA (rRNA) is transcribed from DNA in the nucleolus. rRNA is processed into three mature RNAs and together with proteins form ribosomal subunits. After subunits form the ribosomes, they are transported out of the nucleus to the cytoplasm where they take place in translation.</span>
