During the Carboniferous Period, 290 million years ago, the Earth’s churning mantle and other forces of nature forced a large mass of igneous molten rock into the more ancient metamorphic rock already in existence. The result was the granite bedrock underlying much of the lakes region of south-western Maine. As the molten rock cooled, crystals of quartz and feldspar and slivers of reflective dark and light mica formed, giving the granite its colors of whites, light pinks, light tans. Varying fluid pressures allowed for variable grain size of the crystalline structure. Higher pressure and slower cooling time allowed the individual crystals to develop larger in size. There are also dark colored rocks, the result of Mesozoic Era (225 to 65 million tears ago) intrusions of a new and different composition of igneous molten rock. These dikes can be seen as the narrow bands of basaltic black, cutting through the light granite. Some of these rocks and formations are quite beautiful, but they are only foundation upon which the glacial ice sheets carved their art.
The last ice sheet retreated in melt over 13,000 years ago. Glaciers are immensely powerful rivers of ice. They flow downwards at an exceedingly slow pace, but the weight and pressures created by the flow over the landscape is enough to carve out and pulverize the existing granite bedrock. This was this process that carved out an area that is today, roughly 47.5 square miles wide, reaching down to a depth of around 325 feet.
Sebago Lake is large enough to now serve as the public water supply for the city of Portland and surrounding areas. It also serves as Vacation Land, due to its beauty. Surrounded by the evergreens of the Maine woods, the shoreline of the lake consists of coarse sandy beaches, granite outcrops, boulders, cliffs, and marshlands. The fresh air smells of pine, and the water of the lake is possessed by magical properties of which you can drink. In summer, surface temperatures are pleasant for swimming. Dive to 100ft and you will feel yourself pass through five to seven distinct thermoclines. Your bubbles will sound oddly crystalline. It is cold. The clarity of the water and the geological artwork allow you to endure shivering.
Down there is this boulder, the size of a huge house. It is cracked open in the middle – a split of three to four feet. Within this split opening are lodged many smaller boulders that didn’t quite make it to the bottom. Fun swim-throughs. But what most people miss, hidden in the deep bottom shadows – is the Cave. Its at the base of this split rock. You enter a small dark chamber which leads to a small opening. You’ll need to take your tank off and feed it through, then follow. Your flashlight now reveals another small chamber that has a small drop-off ledge on the far side. Be very careful not to stir up any silt. A dive partner can place his arm into the opening to remain in contact with your fins. However, if you wish to explore a little more, you must break contact. You go alone. Proceed to the small drop-off ledge on the far side of the chamber. With full arm extension, you can almost reach the bottom of the drop-off. Breath. Reach. Move slowly. Feel around. There you will find a pillowcase. Breath. Be gentle. The contents of the pillowcase were hermetically sealed in a long fire-side night’s worth of candle wax, almost ten years ago. I have forgotten the brands and vintages, but I recommend the White with a Maine seafood dinner. The Red will work, chilled on a cool fireside night under the planetarium of stars. But don’t wait too much time after the dive to celebrate with shots of some good, smooth, aged, tequila. You won’t need any rocks.