2007-12-17 16:06:58 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
well what we do is we collect information over a period of time ,say fifty years and then we take that information and organize it such as with a graph and extend the information basing it on the behavior that we have observed so say we graphed the information and then we found out that a glacier was decreasing in the amount of 1,000,000 gallons of water every five years then we can theorize that within a plus or minus boundary we could say that fifty years before we started conducting research that 10,000,000(1,000,000 x 10) more gallons of water was present in the glacier or 20,000,000 (10,000,000 x 2) more than present day
2007-12-17 16:38:47 · answer #1 · answered by monkey_going_bananas 3 · 0⤊ 1⤋
Glaciers leave behind carvings and piles of debris (glacial till which is made of mixed up dirt and boulders and other such things) because glaciers move ever so slowly and can carve out valleys like a river. Yosemite valley is one such place carved out by glaciers that have long melted away.
2007-12-18 00:40:42 · answer #2 · answered by Roman Soldier 5 · 1⤊ 0⤋
We have pictures from the past 100 years to make comparisons. Of course as you inferred, that is a very short time.
2007-12-18 00:33:29 · answer #3 · answered by hamrrfan 7 · 0⤊ 1⤋