The drift and the lobes: the carried ground at its thickness, and the three lobes that met here

INDIANA GEOLOGICAL SURVEY COUNTY WORK, AS BANKED IN THE-LAND.HTML · FRAME NOT RE-LITIGATED

The frame, restated once so the detail has somewhere to stand. Henry H. Gray's Physiographic Divisions of Indiana (Indiana Geological Survey Special Report 61, 2000) divides this township's two-part ground between two of his sections, and The Land prints the survey's names and no others. The riverfront is the St. Joseph Drainageways — “an extensive alluvial plain that lies along the northern border of the state and that is bounded on the south by the Plymouth Morainal Complex” — whose rivers “collected meltwater from the Lake Michigan, Saginaw, and Huron–Erie Lobes of the Late Wisconsin glacier and for a time directed that drainage down the Kankakee Drainageways”, until, when the ice began to clear the Lake Michigan basin, “drainage was diverted into the present lower course of the St. Joseph River, hence the bend at South Bend.” South of the plain stands the Plymouth Morainal Complex itself. That division is banked; this article extends it and does not re-argue it.

The lobes, named and placed. The complex was, in Gray's sentence as banked, “built by ice of three lobes — the Lake Michigan Lobe on the northwest, the Saginaw Lobe on the northeast, and the Huron–Erie Lobe on the southeast.” Three ice streams, arriving from three different basins, met over this county's ground: Lake Michigan ice out of the lake basin to the northwest, Saginaw ice across Michigan from the northeast, and Huron–Erie ice up from the southeast. And here the banked negation governs the article's language exactly: “These did not create a so-called interlobate moraine, but rather competed for space intermittently”, leaving “a jumble of discontinuous ridges and unorganized hummocky topography of moderate relief.” No interlobate framing, and no moraine name from any other city's ground, is imported into Township 37 North, Range 4 East, because no source attaches one to it. The meeting of three lobes is the fact; a tidy interlobate ridge is the story the survey expressly refuses, and this section refuses it with him.

The carried ground at its thickness — the figure the register found missing. The drift beneath this ground is glacial outwash, till and lacustrine sediment at thicknesses “from about 15 to more than 70 meters” — roughly 50 to more than 230 feet — in the Geological Survey's northeastern-county study (United States Geological Survey Water-Resources Investigations Report 95-4041, 1995). That range is the article's thickness finding at first-hand survey strength: not a single depth, because the ground does not have one — a buried, uneven bedrock floor under a plain in the north and a morainal complex in the south carries drift that varies fivefold across a township.south of the St. Joseph River the thickness of sand and gravel diminishes and clay-rich deposits dominate — the outwash riches thin as the ground rises from the Drainageways into the Complex, and clay takes over. The Indiana Department of Natural Resources' county work behind that sentence is The Land leg's to carry at depth; this article's share is the number, the range and the southward change, printed at survey strength.

What is not claimed. No named stratigraphic member or outwash fan is printed for this ground, because none is attached to Township 37 North, Range 4 East in the survey record reached: the register's hope of a named member or fan for this ground is answered by the survey's own practice here, which names sections and complexes (Drainageways; Plymouth Morainal Complex) and materials and thicknesses (outwash, till, lacustrine sediment; 15 to more than 70 metres), not a local member. A subsurface file that did name one — a boring log series or a county subsurface map at member level — is the named settler, and until it is read the member line of this row closes as a NAMED GAP inside an otherwise DUG article: the drift at its thickness, DUG; the lobes at their meeting, DUG on the banked frame; a named member of this ground, GAP, settler the Indiana Geological Survey's subsurface / boring-log files for St. Joseph County. Before the City's rock article said the bedrock “lies under the full thickness of the glacial drift”; this article is where that full thickness gets its number.

Sources:

1. Henry H. Gray, Physiographic Divisions of Indiana, Indiana Geological Survey Special Report 61 (2000) — the St.
2. U.S. Geological Survey, Water-Resources Investigations Report 95-4041 (1995), northeastern-county study — drift thicknesses “from about 15 to more than 70 meters” and the Penn-specific sand-and-gravel / clay sentence.
3. The Land and Before Osceola, banked (frame, rock article) — extended, not re-litigated, per the assignment.