What causes the youngest layers to be on top

When the sediment move and they are being settled somewhere, it means they are being deposited.

After a long period of time, there is a formation of layers of sediments on the top of each other. The weight of the top layer of sediment presses the lower layer and settle down it to the bottom layer, which results in the formation of sedimentary rock.

The oldest layer is on the bottom of the layer and the youngest one would be on the top layer because sediments include living organism, which often contains a fossil fuel.

the organisms are not adapted to live in some communities or habitats.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c