What can explain the presence of a rock layer with no fossils between rock layers with different types of fossils?

The environments in which one rock layer forms and an adjacent later layer forms may be very different from one another. Climates change, sea level rise causes inundation of formerly dry ground, and areas that were once were wet and warm later become dry, or freezing cold, or blazing hot.

Explanation: happy to help you 6th graders :)

not only is it colder, it also becomes darker, less salty, and more dense.

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.