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Carmel, Indiana is built upon a layered sedimentary sequence derived from various depositional processes, erosion, and re-sedimentation. The landscape is mantled by Peoria Loess except where it's dissected by White River and its tributaries resulting in a gently rolling landscape. The rolling landscape extends from the nearly flat uplands of the Tipton Till Plain down to the stream valleys of the White River and its tributaries.

These tributaries have deposited alluvium in the bottomlands along them. Alluvial deposits are generally variable due to the local river-flow conditions during the times the alluvium was deposited, and abrupt changes from coarse-grained to fine-grained sediments both vertically and laterally in the subsurface. Secondary alterations due to systematic weathering are variable due to the lateral extent and sedimentary nature of the alluvium.

The surficial glacial sediments are regionally mapped and named as the Trafalgar Formation. These glacial deposits consist primarily of fine-grained, cohesive diamicton. The Trafalgar Formation is typically a few tens of feet thick. The upper portion of the diamicton is variably bedded and believed to be deposited in an ice-marginal depositional environment; plus the oxidized weathering zone extends throughout the bedded diamicton. The lower portion of the diamicton is massive, uniform, and unoxidized.

Below the Trafalgar Formation is bedded sand informally referred to as 'Glaciofluvial Deposits.' The layered sands comprising the Glaciofluvial Deposits are interpreted to have been deposited by glacial meltwater streams either after the Massive Pre-Trafalgar Formation was deposited or before the glacial advance that deposited the overlying Trafalgar Formation. Where completely penetrated in drilling for this project, the Glaciofluvial Deposits are over twenty to nearly forty feet thick.

The oldest sediment layer encountered during the drilling program consists of glacial deposits here referred to as 'Massive Pre-Trafalgar Formation.' Thickness ranged from eight to seventeen feet and was dominated by matrix-supported diamicton that was mostly massive, with few exceptions with beds of variable lithologies.

Beneath the glacial deposits is bedrock. The bedrock mapped beneath most of the northern part of the project area is limestone, dolomite, and argillaceous dolomite bedrock of the Silurian-age Wabash Formation, but part of the southern project area is mapped as dolomite and limestone bedrock of the younger Devonian-age Muscatatuck Group.

References:
Midwest GeoSciences Group, 2017, Subsurface Investigation for Hydrogeologic and Geotechnical Report for the Board of Public Works, City of Carmel, Indiana.

Undisclosed Project, 2022, Engineering Assessment and Geotechnical Report, Main Street and Rangeline, Carmel, Indiana.

Undisclosed Project, 2024, Engineering Assessment and Geotechnical Report, Illinois Street, Carmel, Indiana.

See the field log of Page 1

See the field log of Page 2

See the Soil Core from 16.5 to 24.0 feet deep

Tim Kemmis and Corrie Meyer discussing the
geologic sequence below Carmel, Indiana