1. The Origin of Squam Lake: A Story of the Structural and Glacial Controls that Shaped this Iconic Lake by Erica Lehner

2. Squam Lake Located in Central New Hampshire 7 miles across & 4.5 miles wide Maximum depth: 99 ft

3. New Hampshire

4. Squam Lake

5. How did it form? Sedimentation Deformation Glaciation

6. Sedimentation Prior to the Silurian (~500 million years ago; ma) East coast of Laurentia was a passive margin Covered in shallow seas  led to the formation of shales and sandstones which have since largely been metamorphosed Located near the equator

8. Mountain Building Northern Appalachian region largely formed from 2 mountain building events Taconic Orogeny (Ordovician ~460 ma) Acadian Orogeny (Early Devonian ~400 ma)

10. Taconic Orogeny Acadian Orogeny

12. Merrimack Syncline (Folding) Massive scale syncline Deformed turbidites & lesser black shales Deep water deposition From the ocean basin that closed and caused the Acadian Orogeny Concave fold from the Acadian Westernmost reaches underlie Squam Lake

14. Intrusion New Hampshire plutonic series Emplaced at the end of the Acadian Orogeny Squam is underlain by the Winnipesaukee Quartz Diorite pluton

16. Littleton Formation Most widespread bedrock in the area Encompasses the Merrimack Syncline and was intruded by the Winnipesaukee pluton Metamorphosed shales and sandstones from the Silurian Made up of mica schists and quartzites Winnipesaukee Pluton intrudes this

17. Glaciation Last glacial maximum was ~21,000 years ago Laurentide Ice Sheet reached to Long Island and Cape Cod in the Northeast of the United States As the ice sheet advanced, it picked up loose sediment and debris, and scraped away at the land, gouging out lakes and scraping mountains As it retreated, it revealed the scoured-out basins and left piles of glacial sediments (till) in its wake

18. Late Wisconsinan Glacial Ice

19. Direction of Glacial Flow & Scour Squam Lake Lake Winnipesaukee N

20. Thank you!