Pronunciation: [tˈa͡ɪd mˈɑːk] (IPA) 
The spelling of the phrase "tide mark" comes from its phonetic sounds. In IPA phonetic transcription, the word is pronounced as /taɪd mɑːk/. "Tide" has the long "i" sound, represented by the symbol /aɪ/, while "mark" has the long "a" sound, represented by the symbol /ɑː/. When brought together, these sounds create the word "tide mark". This term refers to the high point on a beach where the water has reached during high tide.
The term "tide mark" refers to a distinct line or mark left on a surface, particularly along the shoreline or the edge of a body of water, where the water level of tides or waves reaches and recedes. Also known as the high-water mark, it is the visible boundary that indicates the highest point reached by the water during a specific period, usually the highest tide or storm surge.
The tide mark is often seen on sandy or rocky beaches, riverbanks, or coastal structures. It serves as evidence of past water levels and can provide valuable information about the regularity, intensity, or frequency of tides in a particular area. The mark is typically darker and dirtier than the surrounding surface, signifying the accumulation of sediment or debris carried by the water.
As the tide rises and falls, the mark shifts accordingly, tracing the water's movement. In some cases, when a high tide coincides with a storm or extreme weather event, the tide mark can become more prominent and easily distinguishable due to the additional force or volume of the water.
Tide marks are not only significant from a geological perspective, but they can also provide invaluable information to coastal dwellers, scientists, and researchers studying coastal erosion, sea-level rise, or the impact of climate change on oceanic systems. By studying the tide marks, scientists can gain insights into historical water levels, assess shoreline changes, and predict future patterns and their potential consequences.
The word "tide mark" has a relatively simple etymology. It is a combination of the words "tide" and "mark".
"Tide" is derived from the Old English word "tid", which referred to a time or period. It ultimately comes from the Proto-Germanic word "tīdiz", meaning "division of time". The word eventually evolved to specifically mean the periodic rise and fall of the sea caused by gravitational forces exerted by the Moon and the Sun.
"Mark" stems from the Old English word "mearc", which denoted a boundary or sign. It can be traced back to the Proto-Germanic word "markō", with similar meanings.
When combined, "tide mark" refers to the line or boundary left on a surface, such as a beach or a vessel, by the regular rise and fall of the tide.
