The World YDT TGT EarthCache EarthCache
The World YDT TGT EarthCache
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Placed for GC46HYP on April 21, 2013 We are GO for CITO! event. Please Cache In Trash Out as you complete this series to keep the area beautiful for all that visit here. Thank you!
Placed with permission from Topsham Parks and Rec, the Yaruhha Dwarven Treasure geocache series, YDT, is part of the Topsham GeoTrail, TGT, in Maine, USA. The theme of the YDT was inspired by the story for the Dwarven Treasure Geocoin - Yaruhha Edition created by Gregson Vaux Artifacts. This series is designed to allow geocachers to find twelve geocaches and three EarthCaches on foot at one stop, the Topsham Recreation Fields.
Please send a message with the answers to the following questions to claim this EarthCache.
1. From the diagrams of the Glacial Recession in Southern Maine, 16,000 years ago, the distributary stream flowed into what? What do you think that area looks like today?
2. 15,000 years ago, the diagram shows an island forming. By 13,000 years ago, what had this island become?
3. A drumlin is a low, smoothly rounded, elongate hill. Drumlins are deposits of compacted till that are sculpted beneath the ice of a flowing glacier. The long axis of a drumlin parallels the flow direction of the ice. How many years ago did drumlins begin to form in Southern Maine? In which direction do you see evidence of drumlins in this area?
4. Till is an unsorted sediment deposited directly by a glacier and not reworked by meltwater. How many years ago did till cover most of the land in Southern Maine? Do you still see evidence of till in this area?
Thank you for visiting The World YDT TGT EarthCache!
From the Kiosk in the main parking lot:
Near the end of the last great ice age, retreating glaciers reached the present-day coast of Maine. The weight of glaciers compressed the Earth’s crust and combined with glacial melt waters raised water levels to the glacier’s edge. As land was freed from heavy ice cover, it began to rise to its former position and emerged from the sea. About 14,500 years ago a strong pulse of glacial melt water was released, causing sea level to rise even more rapidly. Sea level in this region rose at the same rate as the Earth’s crust was rising. A period of equilibrium resulted in the ancestral Androscoggin River depositing a layer of fine sand, commonly known as a delta, now known as the Brunswick – Topsham sand plain, into the sea. In Topsham, the elevation of this delta can be seen at the Riverside upper playing field and extends to the north almost to the Cathance head of tide area. As the rise of sea level slowed and the land continued to emerge, the Androscoggin began to cut down into the delta surface.
The Riverside lower playing fields sit on terraces cut by the river. Based on archaeological studies in this area, the terraces were cut some time prior to 9,500 years ago.
16,000 years ago a continental glacier covered most of Maine, but was receding from the coastal lowland. The sea was in contact with the ice margin.
15,000 years ago, the glacier was receding rapidly and Southern Maine was ice-free. The land was still depressed from the weight of the ice, resulting in the extensive submergence of low land areas.
13,000 years ago, the glacier had disappeared from central and southern Maine. Uplift of the land had caused the sea to retreat.
Additional Hints
(Decrypt)
Uvag sbe LQG V=J