Discussion on Genetic Terminology for Fluvial Terraces

近年來岩石河階的研究發現，在絕對海水面變動影響小、構造運動持續穩定抬升的環境下，氣候變遷所造成的沈積物通量與河流流量變化，可能影響岩石河階的發育。本文收集上述環境下的全球岩石河階研究個案，歸納出三種岩石河階的發育模式。從這三種模式與岩石河階定年的資料中發現，岩石平台(strath)與岩石河階(strath terrace)有可能在冰期與間冰期交替時期，或者是在冰期中的冷暖期交替時期形成。根據這些研究的結果，我認為當岩石河階的發育可受氣候變動控制時，Bull(1990)所提出的河階分類便出現了問題，特別是Bull(1990)認為岩石河階等同於構造河階，容易使研究者在詮釋河階的成因時產生了先入為主的觀念。因此，建議在進行河階研究時，使用描述性的河階詞彙即可，至於河階的成因則依個案的情況來詮釋。

關鍵字

岩石河階；河階成因；氣候變動；地形演育

並列摘要

Recently evolutionary studies of strath terrace point out that in the environmental settings with minimal sea-level effects and relatively long-term steady tectonic uplifting, climatic fluctuations-controlled variations in sediment flux and river discharges could influence the formation of strath terraces. In this article I collected case studies from such an environmental background globally, and summarized three conceptual models of strath terrace formation. The models and strath terraces dating data indicate that bedrock straths or strath terraces could be formed possibly in the transitions from glacial periods to interglacial period, or from stadial to interstadial interval. According to the findings of the strath terrace studies, I question the classification of fluvial terrace proposed by Bull (1990). Especially, Bull (1990) implied that strath terrace and tectonic stream terrace are synonymous. Therefore, I suggest that it would be appropriate to simply use descriptive terminology for fluvial terrace in literatures, and interpret fluvial terrace genesis case by case.

並列關鍵字

strath terrace ； fluvial terrace genesis ； climatic fluctuations ； landscape evolution

參考文獻

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