earth science

Glacial Lake Iroquois

Glacial Lake Iroquois is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Glacial Lake Iroquois rather than just read about it. In short: Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago. Description The lake was essentially an enlargement of the present Lake Ontario that formed because the St.

Key takeaways

Glacial Lake Iroquois belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Glacial Lake Iroquois to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Glacial Lake Iroquois from memory before moving on to harder problems.

Reference excerpt

Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago.

Description

The lake was essentially an enlargement of the present Lake Ontario that formed because the St. Lawrence River downstream from the lake was blocked by the ice sheet near the present Thousand Islands. The level of the lake was approximately 30 m (~100 ft) above the present level of Lake Ontario. The lake drained to the southeast, through a channel passing near present day Rome, New York. The Rome Sand Plains has several sand ridges that geologists think were formed at this time. The channel then followed the valley of the Mohawk River to the Hudson River. The lake was fed by Early Lake Erie, as well as Glacial Lake Algonquin, an early partial manifestation of Lake Huron, that drained directly to Lake Iroquois across southern Ontario, along the southern edge of the ice sheet, bypassing Early Lake Erie. The subsequent melting of the ice dam produced a sudden lowering of the lake to its present level, a potential trigger for the Younger Dryas episode. The resulting flood also created the Narrows in New York City, destroying the part of the moraine then uniting Staten Island and Brooklyn.

Remnant shorelines Two ancient shorelines in the Toronto area mark the existence of former glacial lakes. About 2 km inland from the shore, a ridge known as the Iroquois Shoreline can be discerned. The old shoreline runs west-east, running roughly parallel to Davenport Road just south of St. Clair Avenue West. Further east, the Scarborough Bluffs also formed part of the shoreline of the ancient lake. In Mississauga, the shoreline is found south of Dundas Street and most visible with hills found east and west of Mavis Road. Another ancient shoreline exists between 2–4 km offshore of Toronto. It is known as the Toronto Scarp and formed the shore of Glacial Lake Warren or Admiralty Lake. From Bluffer's Park in Scarborough to just west of Hanlan's Point is an underwater bluff. In Hamilton, Ontario the Burlington Heights represents a sand and gravel bar formed across the mouth of Cootes Paradise, at the western end of Glacial Lake Iroquois. In New York, Ridge Road and New York State Route 104 run from west to east along a ridge of the old shoreline of Lake Iroquois.

See also Lake Agassiz List of prehistoric lakes Lake Coleman

References

External links History of Lake Iroquois Lake Iroquois and its shore cliff, showing map of the lake Deglaciation of the Central St. Lawrence Lowland

Illustrations

Worked examples

Example 1 — a first encounter with Glacial Lake Iroquois

Start with the simplest possible case. Write down what Glacial Lake Iroquois claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Glacial Lake Iroquois before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Glacial Lake Iroquois ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Glacial Lake Iroquois

In research: Glacial Lake Iroquois appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Glacial Lake Iroquois in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Glacial Lake Iroquois is common in secondary-school and first-year university syllabi. It links to neighbouring topics Geology of New York (state), Glacial lake outburst floods, Glacial lakes of Canada, so understanding it makes those chapters shorter.
In everyday life: Look for Glacial Lake Iroquois outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Glacial Lake Iroquois in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Glacial Lake Iroquois means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Glacial Lake Iroquois out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Glacial Lake Iroquois in simple terms?

Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago. Description The lake was essentially an enlargement of the present Lake Ontario that formed because the St.

Why does Glacial Lake Iroquois matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Glacial Lake Iroquois?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Glacial Lake Iroquois.