When you ask yourself, how on earth did this valley get here?

By BILL CHAISSON
By Bill Chaisson

I love the terrain function on Google Maps. It shows you the topography using shaded false perspective and contour lines, which is a lot of fun when you can toggle back and forth among that view, the political map view of roads and building lots, and the satellite image view. The other day I was watching a recording of the May 28 meeting of the Claremont planning board and they were talking about the permitting process for a proposed transfer station on Industrial Boulevard, between the airport and the railroad tracks. As I often do, I asked myself “Why is this infrastructure where it is?” and I looked at Google Maps to see where it is with respect to the shape of the land. It turned out to be interesting.

Two days ago Glynis Hart wrote a story about the meeting and it was on the cover of our Tuesday edition. Today (yesterday as you read this) the planning board is touring the site to get a better idea of whether or not what is planned is appropriate. The site will receive construction and demolition debris daily, it will be sorted, and the recyclables removed to sent into a separate stream. The balance will be loaded into rail cars and brought to a landfill in the Midwest.

The rail car part is what intrigued me. Railroads cannot go up steep inclines or around sharp corners, so the builders find the flattest, straightest possible route through a landscape. In New England that can be hard to come by. Dale Swenson of the Newport Historical Society told me the story of the monumental project that allowed the railroad to get from Bradford up into Newbury. An enormous amount of blasting had to be done in order to decrease the slope to something a train could climb without slipping backward.

All that blasting is expensive and dangerous, so railroads prefer to follow the natural topography and do a minimum of alteration. Such is the case with the Industrial Boulevard site. When you turn on the terrain feature of Google Maps, you can see that the railroad was built along a natural valley that leads from the Amtrak station over to Mulberry street. The main north-south rail line continues north from the Amtrak station through the valley between Barber Mountain on the west (next to the Connecticut River) and Twistback Hill (just north of the airport). When it gets to the Sugar River Valley, it crosses it on an impressively large and high bridge. This is to say that the Sugar River has eroded down an impressively deep channel. This is noteworthy and I’ll return to it.

The east-west lowland is the fascinating feature here. What made it? Meadow Brook, the present occupant of the valley, could not have made it by erosion. The valley is too deep and too wide and Meadow Brook is too small with too insignificant a drainage to ever have been big enough. The source of Meadow Brook is a little pond just south of the airport. The valley continues eastward from there to a height of land just south of Goulet Avenue. Beyond that height of land is the drainage of the Sugar River.

After the retreat of the last ice sheets between 18,000 and 14,000 years ago, the Connecticut Valley was filled with a huge body of water called Lake Hitchcock. The ice had depressed the land by several hundred feet, so a dam made of glacial moraine at New Britain, Connecticut held back water all the way up to St. Johnsbury, Vermont. The shoreline of Lake Hitchcock in this area was at what is now about 550 feet above sea level. That would put downtown Claremont and the airport underneath the lake, accumulating sediment, and it would drown the Sugar River valley. The gullies that we see in this area, like the ones in Moody Park and the one in which Industrial Boulevard sits, were probably carved over a very short period of time about 12,000 years ago when the post-glacial lake drained.

It’s funny sometimes where watching a planning board meeting will take you.

Bill Chaisson is the editor of the Eagle Times.