Landfill_Stratigraphy

Landfill, Stratigraphy, and Geologic Time:

A Practical Application of the Principles of Stratigraphy

Forensic Geologists Use Scientific Laws to Indict Polluter

Laboratory Exercise

Aim: How can we practically apply the principles and methods by which earth scientists determine

geologic history to provide evidence of illegal dumping?

Instructional Objectives

1. Students should be able to define and demonstrate an understanding and practical application of the

following vocabulary terms and the concepts they convey: uniformitarianism, sediment, stratum, (bed/layer/

horizon), strata, original horizontality, superposition, cross-cutting relationships, geologic column, relative

dating, absolute dating, geochronology, geologic time scale, fossil, index fossil, evolution, extinction, correlation,

hiatus, unconformity, faunal succession, and erosional surface.

2. Students should be able to demonstrate the ability to observe and interpret subsurface data by creating

an accurate stratigraphic column from written as well as physical sources and evidence.

3. Students should be able to demonstrate the ability to date, in relative and/or absolute terms, a vertical

succession of layered materials that has neither been overturned nor deformed.

4. Students should be able to demonstrate the ability to interpret the history, general sequence, and

chronology of events of a region by an investigation of a vertical succession of layered materials deposited at

the site over a specified period of time.

5. Students should be able to demonstrate the ability to follow instructions and sequence information.

Introduction

The purpose of this laboratory activity is to provide the evidence necessary to either indict or exonerate a

suspected, notorious local polluter. This activity, therefore, should be thought of as a search for indisputable

evidence of illegal dumping to be used in court. Regents Earth Science and Geology students are required to

think and behave like detectives, searching for and interpreting clues, while being ever-mindful of the principles

of stratigraphy and methods by which earth scientists deduce geologic history (hence the term "forensic geology").

There are many similarities shared between the alternating layers of earth and rubbish in a landfill and the layers

of sedimentary strata which accumulated in a sedimentary basin, as well as the correspondence between fossils

and anthropogenically-produced solid waste. The extrapolation of buried newspapers, for instance, or any other

material which may give indisputable evidence of time of formation (perhaps even time of burial) and their

remarkable correspondence to index fossils should be clearly understood. Such an interpretation will assist you

in understanding the pivotal importance of these features in developing a chronology of events and thereby

interpreting the history of a given location based on the accumulation of everything from mineral detritus to

garbage, to many other types of surface materials that become buried and preserved at or near the Earth's

surface.

As the geologist works to develop a model of the Earth's history, he or she attempts to place events in

chronological order - that is - in order of which events happened first, then second, and so on. The geologist

attempts to find the relative age of a rock or event - its age compared with that of other rocks or events. The

geologist also attempts to find the actual, or absolute age, which is the date that an event occurred or a rock

was formed.

Before we advance into a discussion of how earth scientists sequence past geologic events, there are three

basic principles, or "laws", of earth science that have arisen from a study of sedimentary rocks and processes

that should be restated. These laws are uniformitarianism, original horizontality, and superposition.

Uniformitarianism. Any discussion of geologic history, whether a period of hundreds or hundreds of millions

of years, necessitates analysis of features and description of events of the past in terms of contemporary

geologic processes. We assume that the forces at work on the Earth have not changed with time. Rivers, for

example, were not only present in the distant past but developed, behaved, and produced features in the same

fashion as modern river systems. Simply put, the uniformitarianist's credo as so eloquently stated by Scottish

geologist James Hutton over 200 years ago - "the present is the key to the past" - is the cornerstone of modern

geological thinking. Therefore, by observing the geologic processes now at work on the Earth, it is possible to

decipher geologic history as written in the textures, minerals, and fabrics of rocks.

Original Horizontality. Sedimentary rocks for from the deposition, compaction, and cementation of

sediments that settle through a column of fluid. Sediments that are generally deposited in slowly or nonmoving

fluids accumulate at the bottoms of rivers, lakes, oceans and terrestrial basins in flat, parallel, horizontal layers.

This tendency of most sediments deposited under such conditions (and not on sloping surfaces) is called

original horizontality. In other words, geologists assume, for the most part, that the individual layers or strata of

most sedimentary rocks were originally deposited as horizontal blankets on the bottom of a basin. Therefore the

individual rock layers, as well as their bounding surfaces, originally possessed a horizontal orientation

Superposition. If we accept the principle of original horizontality, it is simple to infer that in a vertical

succession of sedimentary strata that have neither been overturned nor otherwise strongly deformed, the oldest

layers reside at the bottom and the youngest layers rest at the top. This is the principle of superposition. Since

sedimentary strata resemble and are formed in much the same fashion as layers in a birthday cake, it is a

simple matter of logic to understand that the lowest (or relatively "oldest") layer of cake has to be deposited on

the plate first. Each new layer, therefore, is relatively younger than the layer beneath but older than each

subsequent layer. Superposition, therefore, allows the relative dating of sedimentary strata.

Vocabulary:

a. uniformitarianism _________________________________________________

b. sediment _______________________________________________________

c. stratum (bed/layer/horizon) _________________________________________

d. strata __________________________________________________________

e. original horizontality _______________________________________________

f. superposition ____________________________________________________

g. cross-cutting relationships _________________________________________

h. geologic column __________________________________________________

i. relative dating ____________________________________________________

j. absolute dating ___________________________________________________

k. geochronology ___________________________________________________

l. geologic time scale _______________________________________________

m. fossil ___________________________________________________________

n. index fossil ______________________________________________________

o. evolution ________________________________________________________

p. extinction _______________________________________________________

q. correlation ______________________________________________________

r. hiatus __________________________________________________________

s. unconformity ____________________________________________________

t. erosional surface _________________________________________________

Materials:

one set of instructions and lab data

one report sheet

pencils with erasers

colored pencils

one box of labeled core material retrieved from the Swarm o'Seagulls Landfill (optional)

one magnifying lens (optional)

Tasks:

Your first task is to plot an accurate stratigraphic column of the Swarm o'Seagulls site using your own

system of symbols or ornamentation to describe the content of material exhumed from each rubbish layer.

Accurately plot the data in the column space provided. Depths in 10-foot intervals have been provided for your

reference.

Your second task is to carefully study your evidence and try to determine if Big Louie has violated his

contract with the borough to stop dumping at the site after February 1, 1985 by strictly applying the three laws

of stratigraphy to your analysis of the subsurface materials excavated from the dump: uniformitarianism, original

horizontality, and superposition. Faunal succession may also be a helpful guide to interpretation. (Hint: You

should also try to think of some of the samples as index fossils that provide indisputable evidence of maximum

time of deposition or, in this case, the maximum time of dumping.)

The borough is counting on our expertise in stratigraphic analysis and "forensic geology" to help them

maintain a healthy environment for the people of southern Brooklyn. Bear in mind that Big Louie will have a team

of lawyers and his own consulting geologists standing by who will attempt to dismiss our evidence and refute our

claims if they are not in his favor. The success of our client's case depends upon how successfully we apply and

how stringently we adhere to our stratigraphic "laws" in the analysis of our data.

Good luck. We'll need your reports a.s.a.p. in order to prepare our final report for courtroom presentation.

Dewey & Klimetz, P.C.

Civil Engineers, Urban Planners and Waste of Our Time Specialists

Top of the Pyle

New York City

Telephone: (212)-We-Dig-Dumps

Fax: (212)-We-Take-Cash

URGENT

CONFIDENTIAL INTEROFFICE MEMO

From:

Mr. Dewey and Mr. Klimetz

To:

All Employees in the Stratigraphy Department

Date:

February 15, 1997

Re:

Alleged Illegal Dumping of Solid Waste and Mixed Household Refuse at

the Swarm o'Seagulls Landfill in Brooklyn by Big Louie's Carting

(Motto: "If It's Large, Smelly, and Gooey, Think of Big Louie").

We have been hired by the Borough of Brooklyn to determine if Big Louie's Carting has

been conducting illegal dumping at the Swarm o'Seagulls Landfill. Big Louie's has been the only company allowed to dump solid refuse at the site since it opened in 1965. The company was also responsible, by contract, for providing supervision at the site to ensure (1) that no unauthorized dumping would take place, and (2) the safety of the public and surrounding community. Big Louie's contract with the borough stipulated that dumping was to be allowed for a period of only 20 years. That is, after February, 1985, there was to have been no further dumping by Big Louie (or any firm) at the site although Big Louie's responsibility for site security is to remain in effect until the year 2005.

The communities surrounding the dump, however, have frequently complained to the borough of being awakened in the middle of the night by the sound of large dump trucks with the Big Louie's name and motto painted on the doors, covered with large canvasses, entering and leaving the site. When questioned about his workers' nighttime activities, a spokesperson for Big Louie's said that the trucks were only carrying earth and sand to fill-in the site where settlement of the ground had occurred.

We have been hired by the borough to determine of Big Louie has been dumping on Brooklyn. A team from our Site Investigation Department has collected some subsurface samples from the dump for analysis. They were collected from a single three-foot-square pit dug vertically downward from the surface to the floor of the dump, that is, to a depth of 100 feet. (A detailed data list of the samples, as well as the depths at which they were collected, is listed on the following page).