Magnetic susceptibility is one of the most important methods for monitoring of sediment composition changes in environmental studies. In this survey, in order to do sedimentological studies and determine the Caspian Sea (Gorgan Bay) level fluctuations by variations in magnetic susceptibilities 5 cores were taken from bottom sediments, from East to West. These samples were analyzed for grain size, total organic matter content, carbonate content, and magnetic susceptibility (MS). The results showed a close relationship between particle size distribution and MS magnitude due to variation in detrital influx, caused by sea-level fluctuations in different times. This process is reflected in increasing particle size and magnitude of MS simultaneously with sea level fall and decreasing particle size (increase mud) and magnitude of MS simultaneously with sea-level rise. Moreover, relationship between magnitude of MS and carbonate contentwas not observed.using magnetic susceptibility curves with other data, including geological and historical data, can be a suitable idea for the reconstruction of marine environments, especially near the coastal area.

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