The tsunami triggered by the earthquake of May 22, 1960, flowed violently into the Maullín River estuary. According to eyewitnesses, the tsunami deposited a widespread sand layer throughout the estuarine marshes. The aim of this study was to determine whether the sand sheet was incorporated into the estuarine stratigraphy. A sedimentological analysis of the sand, located on a saltmarsh opposite Maullín, was carried out. The sand layer was found between the 1960 saltmarsh and the present soil. Considering the sand sheet grain size characteristics and tilt of the buried vegetation, it is probable that the sand was transported from the neighboring dunes and/or sandbars located in the estuary mouth. The spatial distribution of granulometric parameters shows that the marsh vegetation reduced the wave transport capacity during seawater run-up. This illustrates the importance of estuarine marshes in diminishing the impact of tsunamis.El tsunami generado por el sismo del 22 de Mayo de 1960 se propago aguas arriba del estuario del rio Maullin. De acuerdo a testigos oculares, este evento deposito una extensa capa de arena en las marismas. Con el objetivo de reconocer si la lamina de arena tsunamica forma parte de la estratigrafia del estuario, se realizo un estudio sedimentologico de una marisma ubicada frente a Maullin. Se reconocio el estrato tsunamico entre la marisma de 1960 y los depositos actuales del estuario. Considerando las caracteristicas granulometricas del deposito psamitico y la inclinacion de la vegetacion sepultada, se infiere que las arenas provienen de las dunas aledanas y/o de los bancos arenosos de la desembocadura del estuario. El comportamiento espacial de los parametros granulometricos indica que la marisma freno el avance de las olas, fenomeno que se habria incrementado por la presencia de vegetacion. Se destaca la importancia de las marismas en la mitigacion del impacto del tsunami.