If a stream cuts through the narrow neck of land separating two meanders, the abandoned meander loops may become isolated to form a/an

oxbow lake

Explanation:

The meander usually originates in the rivers located in the alluvial plains that have almost no slopes due to the sediments of the earth that commonly settle in the convex areas of the meander. However, in the concave areas, thanks to the operation of forces of centrifugal characteristics, greater erosion is generated and the banks are diminished.

If the natural action of the erosion of water and sediments causes two curvilinear channels to be found between them, the river will react through the area where the currents exert opposition and in this way it will originate a horseshoe lake or oxtail (in English usually called oxbow lake) because the sediments will block the entry of water and the exit of the previous meander, which will cause it to be outside the river path.