Patagonia is a key place to analyze the climatic trends (waves and winds) of the Southern Hemisphere. The northern coast of the San Matías Gulf (“Bahía Sin fondo” for the original Spanish descriptions) is characterized by an attached sand barrier developed on top of former cliffs. Morphological features are indicating changes in the regional slope when the sea level drowned the depression of the gulf. An original eastern slope was progressively replaced by slopes towards the south. The availability of sand during the transgression and maximum sea level was directed to the east due to the dominant westerly winds. Sand dunes accumulated on top of former cliffs and today –due to coastal erosion-, remain as cliff-top dunes. A conceptual model for the formation of these cliff-top barriers is described in relation to the fluctuation of the sea level and the sand migration, which was studied through mineralogical analysis comparing the different environments: cliff, beach, and dunes. Their composition explains the sediment transport shift and is locally associated to the Río Negro Formation deposits and regionally to Andean Cordillera volcanic sources.

巴塔哥尼亚是分析南半球气候趋势（海浪和风）的关键地点。圣马蒂亚斯湾的北部海岸（原始西班牙语描述为“ Bahía Sin fundo ”）的特点是在以前的悬崖顶部形成了附着的沙障。形态特征表明当海平面淹没海湾凹陷时区域坡度的变化。原来的东坡逐渐被南坡所取代。由于占主导地位的西风，在海侵和最高海平面期间的可用沙子被导向东方。沙丘堆积在以前的悬崖上，今天——由于海岸侵蚀——仍然是悬崖顶的沙丘。描述了与海平面波动和沙子迁移相关的形成这些悬崖顶屏障的概念模型，通过矿物学分析比较了不同的环境：悬崖、海滩和沙丘。它们的成分解释了沉积物迁移的变化，并且在当地与 Río Negro 组沉积物有关，在区域上与安第斯山脉火山源有关。