Lake Michigan
Our analysis correlates numerous proposed PZ ejecta structures structures - including the Carolina bays and the Goldsboro Ridge - to a Perigee: Zero cometary impact event that struck the Wisconson-era ice shield between 10, 000 and 17,000 years ago. Strong consideration is being given to the period of 12,500 to 13,00 years ago, at the climat shift known as the Younger Dryas Boundary.
The general "rotation" of inbound ejecta trajectory represented in the Eyton & Parkhurst graphic (discussed in the Carolina bays enigma page) is the manifestation of two different factors.
Carolina bay Orientation - Eyton & Parkhurst
The first being the the Earth's rotation during the loft period applied to the main body of bays pointing NW. Ejecta droplets traveling on an eastward great circle route will land slightly further westwardly due to the faster west-to-east ground rotation vector. As a result, their azimuth will "seem" to be directed back towards a point further west than the actual ejection point. This effect will revers if the emplacement site is further towards the pole than the ejection site. Similarly, ejecta traveling to the west will appear to have been
The Carolina Bays display a marked alignment with northwest-southeast being the preferred orientation. Although there are minor local fluctuations, deviations from the preferred orientation appear to be systematic by latitude (Prouty, 1952).(1)
The following Google Earth graphic is our computed trajectory path for this set.
Carolina bay Primary Set Trajectory - linked to higher resolution image
Using the ballistic program Orbit 1.2, a set of orbital parameters were developed which generates a trajectory into lake Michigan The following movie presents the trajectory and the settings. The orbita velocity used is 7.8635 km/sec, and the northerly equator crossing is at a 340 degree (retrograde) direction. Clicking on the graphic will display a short videio of the last moments of the orbit.
Orbital Example
Movies in the chapter subsection "Movies" attempt to re-create the sequence of the first five impactors arriving at Lake Michigan.
Using the same ballistic program, a set of initial conditions were developed which generates a trajectory from lake Michigan into the Goldsboro Ridge vicinity. The following graphic presents the trajectory and the settings. The initial ejection velocity used is 6.51 km/sec, which within the usual range of 5 to 8 km/sec.
The geology of lower Lake Michigan can be viewed as a shallow Perigee-Zero impact crater, formed by a shallow strike into the Wisconsin Ice sheet .
The graphic below presents a view of the glacial coverage of NA at the furthest advance, about 100,000 years ago. We are proposing an ice thickness of approximately 1 kilometer over the Lake Michigan impact site at the time of the event.
North American Ice Sheets
We have theorized that if an impact occurred into a 1k to 2km thick ice sheet, which adsorbed much of the impact energy. Pulverized ice effectively mobilized and hydrated the ejecta, composed of sedimentary strata from the terrestrial crate, along with elements of the impactor. Invoking the Wisconsin Ice Sheet also provides a vehicle to minimize local ejecta, as it would have landed on the sheet, to eventually be carried south and deposited across Indiana and Ohio.The proposed impact energies are far lower than classical energetic cometary impacts arriving from solar orbits. The Perigee: Zero conjecture delivers a stream of cometary impactors at their terrestrial orbital velocities of 7km/sec.
Explanation of Lake Michigan's Glacial Morphology
It is quite appropriate to note that Lake Michigan has provenance as a glacially-carved companion to Lake Huron, as they both exist on the circumference of the Michigan Basin. That subsidence is centered below Michigan’s land mass proper, not below the Lake; the strata under the body of the lake is understood to trend slightly down west to east across the entire width of the Lake. A significant body of knowledge holds that the Michigan basin is a simple ( although “poorly understood” -USGS) geological depression in the earth’s crust, which dragged down the overlying Cambrian, Ordovician and Silurian sedimentary strata (originally laid down horizontally), likely falsifying our conjecture.Other obvious difficulties with attempting to cast Lake Michigan as an impact structure include, among other things: the current understanding of glacial ice sheet retreat has removed most of its bulk from above Lake Michigan prior to our YDB 12.9 kya timeline; older carbon dating of moraines in south of Lake Michigan suggest a geometric shape of the current Lake Michigan southern bowl; the depth of the crater is only 10% of what could reasonably be expected - even considering a 2k ice sheet cover.
Given the highly unlikely eventual proof of Lake Michigan as the causal impact site, an objective result of this exercise might well be the general falsification of either the ejecta conjecture or the the methodology of the alignment methodology discussed in the thread, or both. As our heuristic hunt continues, we are drawn to a site sevearl degrees to the east ot the Lake Michigan area: The Saginaw Bay.
(1) A RE-EVALUATION OF THE EXTRATERRESTRIAL ORIGIN OF THE CAROLINA BAYS by J. Ronald Eyton & Judith I. Parkhurst