ENVIRONMENTAL INVENTORY AND ANALYSIS SECTION 4 ENVIRONMENTAL INVENTORY AND ANALYSIS A. GEOLOGY, SOILS, AND TOPOGRAPHY Table 3 Brookline's Drumlins Brookline's 6.8 square miles (4,355.4 acres) are Elevations above sea level located in the lowlands of the Boston Basin, on average between 50 and 140 feet above sea level. Aspinwall Hill 240 feet However, the many hills that spread across the Corey Hill 260 feet landscape are among the highest points in the Fisher Hill 270 feet basin. At 340 feet, Single Tree (also known as Larz Anderson Park Hill 290 feet Lyman) Hill is the highest point in Town. Mount Walley 310 feet Single Tree Hill 340 feet Continental drift, volcanoes, sea level changes, Walnut Hill 310 feet glaciers, and humans have acted on the landscape over the years to shape the bedrock and surficial Glaciation also left kettle ponds, such as Lost geology of Brookline into its present form. The bed- Pond, and wetland areas across the Town. rock that forms the Town's foundation is of three varieties: Roxbury conglomerate, Cambridge slate, In areas where bedrock is close to the surface, and Brighton melaphyre. The bedrock geology of there is a potential for flooding during heavy rains North Brookline is not well known and outcrops of due to insufficient soil cover. Soil acts like a sponge Cambridge slate, which appears as a dark bluish to soak up and retain rain water. Typically, deeper gray to brownish gray shale or slate, can be seen soils have a greater potential to absorb water. When between Beacon Street and Clark Road and east of the soil reaches its maximum absorption capacity, Cleveland Circle to Tappan Street. Brighton mela- water moves through the soil, and then migrates phyre is a greenish, brownish, or purplish basaltic over the bedrock to lower elevations. In many volcanic rock. Outcrops can be seen near Lost cases, the lowest point may be the basement of a Pond. Probably the best known is the Roxbury con- house. Many bedrock areas have steep slopes. glomerate or "puddingstone" on which most of Removing vegetative cover on steep slopes will South Brookline rests. Numerous outcrops of pud- increase the chance of soil erosion. Future develop- dingstone, which consists of waterworn rocks ments should consider the depth to and location of cemented together with other minerals, can be seen bedrock because it influences site drainage and throughout this part of Town, including in the D. drainage patterns in a given area. Blakely Hoar Sanctuary. Soils Glaciers scoured the land 10,000 to 12,000 years ago. When the ice sheets expanded across The surface geology of Brookline is the result of the landscape, they removed all plant and animal the material or debris left behind by glaciers, ero- life. The coastal areas of New England sank below sion and sedimentation, and human alterations. In sea level due to the great weight of the ice. When general, Brookline soils are either glacial till or sand the glaciers receded, the major features of the land- and gravel. Soils are classified by the U.S. scape we see today remained. The most prominent Department of Agriculture’s Natural Resources features are the drumlins, hills composed of glacial Conservation Service, based on physical and chem- till (rock and clay) formed in the shape of an invert- ical properties in their horizons or layers, such as ed teaspoon and pointing in the direction of the color, texture, structure, etc. glacial flow. Most of North Brookline is classified as one of Brookline has seven major drumlins: Corey Hill, several different types of urban land complexes. Fisher Hill, Single Tree Hill, Walnut Hill, Larz Urban land complexes are defined as areas where Anderson Park Hill, Aspinwall Hill, and Mount 75 percent or more of the land is covered with Walley (Table 3). In addition to the till, glaciers left impervious surfaces. Impervious surfaces consist of deposits of sand and gravel, particularly in the buildings, roadways, parking lots, and are typical of northern and southwestern portions of the Town. 23 ENVIRONMENTAL INVENTORY AND ANALYSIS business, commercial, and industrial areas. B. LANDSCAPE CHARACTER Essentially all the rain that falls in these areas runs off into storm drains that are required to handle the The combination of bedrock outcrops and gla- excess water. Examples of these areas are on cial features, drumlins rising above relatively flat Beacon Street at Washington Square and Coolidge glacial deposits and extensive remnants wetlands, Corner. It is difficult to determine soil types in these and small streams, continue to affect Brookline's areas because much of the soil has been mixed up, patterns of development. As Brookline's landscape removed, replaced with other materials, and resides is largely developed, most of the areas that remain under pavement, concrete, and/or buildings. undeveloped are those where natural features have Development limitations vary because soil types are made development difficult. relatively unknown below the impervious surfaces that cover most of North Brookline. When the imper- The hills which were earlier claimed for estates vious cover is removed there is a risk of erosion. and large homes remain significant, but only a few Without protective controls (e.g., hay bales, silt serve public open space needs. Larz Anderson and fences or other methods), eroded soils can wash Summit Hill are both beloved places to see the sky, into the storm drain and discharge into water watch sunsets and the view the skyline. Larz resource areas like Hall's Pond, Leverett Pond, the Anderson is one of the best sledding hills in Town. Muddy River, and the Charles River. Erosion and Skyline Park, completed in 2008, provides public sediment control practices should be implemented access to a hill with a scenic vista. The Fisher Hill during all phases of construction in these areas. Reservoir has recently transferred in ownership Future developments/redevelopments should try to from the State to the Town of Brookline, and will reduce the amount of impervious areas where prac- eventually be open to the public as parkland and tical and try to incorporate practices to retain rain open space. This area could be landscaped in a water onsite and reduce the amount of runoff to the way that would give visitors a direct view of the sun- storm drain system. set. Public access to the top of those hills that still include open space would be of great value. In South Brookline, there are a variety of differ- ent soil types. Hydric or wetland soils are generally The rock outcrops, particularly the Roxbury classified as Swansea muck, a deep (52 inches or conglomerate in South Brookline, are unique fea- greater) organic soil with a seasonally high water tures of Town. Because they have shaped and table. Much of Putterham Meadows rests on this somewhat limited development, a number of the soil. Allandale Farm contains prime agricultural public open spaces in this part of Town contain soils, including soils in the Canton, Scituate, and interesting outcrops, including Dane Park, Putterham Sudbury series. Prime agricultural soils, including Woods, Walnut Hills Cemetery, and the D. Blakely the Sudbury and Merrimac series, are also located Hoar Sanctuary. However, the outcrops on private south of Sargent's Pond on undeveloped land, property are vulnerable to destruction from expan- which has been used in the past for cultivation. sions and other modifications. Residential development limitations on agricultural soils range from slight to moderate. Putterham At Allandale Farm and on large properties that Woods and Dane Park are characterized by soils in were once part of larger country estates, small por- the Hollis series, which are comprised of a thin layer tions of the flat areas and gentle slopes which were of loamy soil over shallow bedrock. The area not historical wetlands remain as fields or mead- between Fernwood Circle and Warren Street is ows. However, none of these fields or meadows characterized by soils in the Montauk, Hollis, and currently are accessible for members of the public Sudbury series. Generally, they present moderate who might wish to explore these natural habitats. limitations on residential development due to wet- Some can be viewed from public streets and side- ness. walks, but even their role as a viewshed are not protected. Preservation of agricultural land and Soils in the Fisher Hill Reservoir area are clas- meadow lands would serve the public, particularly if sified as Newport Urban Land Complex, which also some limited public access could be granted within presents moderate challenges to residential devel- them. opment due to slope and wetness. The Bournewood Hospital site is located on Charlton Hollis Urban In North Brookline, there was once a cedar Land Complex. Development limitations are gener- swamp, salt marshes, fresh water wetlands, and ally slight except where there are rock outcrops. streams associated with the Charles River and 25 ENVIRONMENTAL INVENTORY AND ANALYSIS Muddy River. Today, North Brookline is extensively and wildlife, as well as suitable for primary contact developed, with Hall's Pond and a number of parks recreation, such as swimming, fishing, windsurfing, and playgrounds acting as the only natural features. and secondary contact recreation, such as canoe- However, many of the parks, including Amory ing, boating, kayaking, and sailing. The last nine Playground, Griggs Park, Brookline Avenue miles of river, known as the Charles River Basin, is Playground, and Boylston Street Playground were one of the most widely used recreational areas in built on poorly drained or filled land. the country. In South Brookline, the draining and filling of Some drainage from North Brookline reaches wetlands, as well as building beside small open sec- the Charles River directly.