Geologia Croatica (Nov 2010)
Frequency Distribution Curves as an Indicator of Evolutionary Trends in Geomorphological Systems: A Case Study from the Northwestern Part of Hrvatsko Zagorje (Croatia)
Abstract
Frequency distribution curves can be indicative of the dynamicsand evolutionary development of geomorphological systems. Normallydistributed geomorphological data are a reliable indicator of theequilibrium fluctuations prevalent within such systems. This occurs,for example, when a delicate balance is established between varioustypes of landforms and geomorphological processes. Landforms thatexist in this geomorphological steady state can be properly called"equilibrium" structures. They show no permanent trends of eithergrowth or destruction. On the contrary, a positively skewed frequencydistribution curve indicates a type of non-equilibrium conditions andnon -linear relationships within geomorphological systems, whichmay be the result of major external energy inputs (particularly fromtectonic uplift ). This in turn gives rise to new and more complexhigher-order landforms. These represent structures of growth or evolution. Alternatively, a negatively skewed frequency distribution curve, also being a consequence of non-equilibrium conditions, indicatesa lack of free energy in the system, which induces destruction ofthe existing landforms. Such landforms represent strucres of degeneration.The fluvial landscape in the northwestern part of Hrvatsko Zagorje, portrayed in terms of an open system, has been used as thegeomorphological framework for this study, the primary purpose ofwhich was to apply frequency distribution curves in the interpretation of the processes influencing the creation and destruction of the landscape. Horizontal and vertical dissection, slope and other morphometriccharacterictics reflect the specific dynamics of the geomorphological processes, which relate a variety of landforms to their geologic framework and climate in the study area.
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