Southern Peninsula Of Michigan Research Articles

The ‘Coal Measures’ of Grand Ledge, Michigan, USA

Abstract The best-exposed natural bedrock outcrops in Michigan's southern peninsula are Upper Carboniferous (Pennsylvanian) sandstone ledges underlain by silts, clays, and coals in classic midcontinent ‘cyclothem’ stratigraphy, exposed along the Grand River in the city of Grand Ledge. Native Americans used the underclay in pottery; later commercial mining was the basis for clay-products factories. In the 1800s, the ledges provided a picturesque setting for a resort economy. Among the beneficiaries of repurposed quarries (now parks) are generations of Michigan geoscience students. A trip to Grand Ledge is often the first geology field experience for many students and plays an important role in the professional development of practising geoscientists and geoscience educators in Michigan. After an announcement of plans to expand the city's water treatment plant, adjacent to the cyclothem exposure, geologists from academia, government, and industry united to support preservation of the outcrops. City officials, previously unaware of the geoheritage value of the rocks exposed in their parks, are willing to work with geoscientists to preserve the site. This experience underscored the importance of documenting the geoheritage of the Grand Ledge area and establishing relationships with those who have oversight of these ‘greatest outcrops’ to ensure their preservation for future generations.

Genetic Variation of the Bloom-Forming CyanobacteriumMicrocystis aeruginosawithin and among Lakes: Implications for Harmful Algal Blooms

To measure genetic variation within and among populations of the bloom-forming cyanobacterium Microcystis aeruginosa, we surveyed a suite of lakes in the southern peninsula of Michigan that vary in productivity (total phosphorus concentrations of approximately 10 to 100 microg liter(-1)). Survival of M. aeruginosa isolates from lakes was relatively low (i.e., mean of 7% and maximum of 30%) and positively related to lake total phosphorus concentration (P = 0.014, r2 = 0.407, n = 14). In another study (D. F. Raikow, O. Sarnelle, A. E. Wilson, and S. K. Hamilton, Limnol. Oceanogr. 49:482-487, 2004), survival rates of M. aeruginosa isolates collected from an oligotrophic lake (total phosphorus of approximately 10 mug liter(-1) and dissolved inorganic nitrogen:total phosphorus ratio of 12.75) differed among five different medium types (G test, P of <0.001), with higher survival (P = 0.003) in low-nutrient media (28 to 37% survival) than in high-nutrient media. Even with the relatively low isolate survivorship that could select against detecting the full range of genetic variation, populations of M. aeruginosa were genetically diverse within and among lakes (by analysis of molecular variance, Phi(sc) = 0.412 [Phi(sc) is an F-statistic derivative which evaluates the correlation of haplotypic diversity within populations relative to the haplotypic diversity among all sampled populations], P = 0.001), with most clones being distantly related to clones collected from lakes directly attached to Lake Michigan (a Laurentian Great Lake) and culture collection strains collected from Canada, Scotland, and South Africa. Ninety-one percent of the 53 genetically unique M. aeruginosa clones contained the microcystin toxin gene (mcyA). Genotypes with the toxin gene were found in all lakes, while four lakes harbored both genotypes possessing and genotypes lacking the toxin gene.

The Importance of Glaciofluvial Features within Michigan's Port Huron Moraine

Abstract Evidence based on topographic quadrangles, aerial photographs, soils maps, and extensive fieldwork indicates that the Inner and Outer Port Huron moraines in the northwestern part of Michigan's Southern Peninsula represent a mega-assemblage of related glaciofluvial formations marking successive marginally stagnant glacial termini. Surficial sediments consist of ice-contact stratified drift and proglacial sand and gravel. Diamictons are very limited in extent and usually occur in the form of flow till. Uppermost sediments within the intervening Mancelona Plain show a transition from coarse, poorly sorted proximal deposits dominated by longitudinal bars to distal, fine-textured, well-sorted braided-stream deposits displaying sandy bedforms. Paleocurrent indicators show that meltwater streams first flowed directly away from the ice margin and then turned 90 degrees to the right (southwest) to flow parallel to the sandur's trend. Based on these data, we propose that what were previously mapped as the ...

The Importance of Glaciofluvial Features within Michigan's Port Huron Moraine

AbstractEvidence based on topographic quadrangles, aerial photographs, soils maps, and extensive fieldwork indicates that the Inner and Outer Port Huron moraines in the northwestern part of Michigan's Southern Peninsula represent a mega‐assemblage of related glaciofluvial formations marking successive marginally stagnant glacial termini. Surficial sediments consist of ice‐contact stratified drift and proglacial sand and gravel. Diamictons are very limited in extent and usually occur in the form of flow till. Uppermost sediments within the intervening Mancelona Plain show a transition from coarse, poorly sorted proximal deposits dominated by longitudinal bars to distal, fine‐textured, well‐sorted braided‐stream deposits displaying sandy bedforms. Paleocurrent indicators show that meltwater streams first flowed directly away from the ice margin and then turned 90 degrees to the right (southwest) to flow parallel to the sandur's trend. Based on these data, we propose that what were previously mapped as the Inner and Outer Port Huron moraines are actually the collapsed upstream portions of the Mancelona and Outer Port Huron outwash aprons, respectively. Although till is present in the subsurface, well‐log data and exposures reveal that waterlain deposits predominate in the upper 50 m of the stratigraphic column. The large volumes of superglacial fluvial drift and apparent absence of well‐integrated subglacial drainage features are consistent with a glacier exhibiting a frozen‐bed margin. Small disintegration ridges associated with major heads of outwash probably record the transition to warmer conditions with final deglaciation. Such relationships agree with recent interpretations of glacial dynamics in the northern Midwest and provide insights into glacial and sedimentological processes associated with a conspicuous and chronologically important moraine centrally located along the southern margin of the Laurentide Ice Sheet.

DRIFT VOLUME IN THE SOUTHERN PENINSULA OF MICHIGAN—A PRODIGIOUS PLEISTOCENE ENDOWMENT

Michigan's Southern Peninsula is by far the largest drift repository in the Great Lakes Area. Thickness of the glacial sediments averages 85 m and volume, previously unknown, exceeds 9300 km3. The distribution, however, is very uneven, as is the underlying bedrock surface. These variations and known surface characteristics provide a basis for the first qualitative and quantitative identification of distinct drift realms. Even the smallest of the eight realms contains about 35% more drift than the better known Kettle Moraine tract of Wisconsin, which encompasses 50% more area. Comparative analysis within the peninsula shows that Pleistocene glaciation completely transformed the topography to the north, whereas the southern half has palimpsest relationships with subcropping formations. [Key words: drift, drift volume, Michigan, Great Lakes, Pleistocene.]

NEW AGE CONTROL ON THE PORT HURON MORAINE IN NORTHERN MICHIGAN

Until now, radiocarbon age estimates of the Port Huron moraine in Michigan have been based largely on 14C dates from beyond the state. This study reports a radiocarbon age of 12,960 ± 350 yr B.P. from sediments immediately proximal to the northwestern part of the Inner Port Huron moraine in Michigan's Southern Peninsula. Geologic relationships indicate that this section of the moraine predates the age estimate. Stratigraphic and morphologic relationships of sediments of ancestral Great Lakes phases related to the Port Huron morainic system, 14C ages from sediments of those lake phases, and a 14C age from wood buried by till of the Wyoming moraine (a morphostratigraphic equivalent of the Port Huron moraine), have collectively supported the interpretation that the morainic system was formed between 13,500 and 12,700 yr B.P. Our radiocarbon age estimate, the first from sediments immediately proximal to the Port Huron system in Michigan, is compatible with this interpretation. Furthermore, because the Port Hu...

Subsurface Stratigraphy of Cambrian Rocks in Southern Peninsula of Michigan: Michigan Basin: ABSTRACT

Rocks believed to be Late Cambrian exist throughout the subsurface area of Michigan's Southern Peninsula. These Cambrian rocks represent the oldest Paleozoic sedimentary deposits in the Michigan basin. Isopach and paleogeologic maps of these Cambrian rock units have been prepared with the data derived from geophysical well logs, descriptive logs, and well samples from 101 oil and gas test wells, mineral extraction wells, and deep disposal wells. A generalized contour map of the Precambrian surface has also been prepared from these data.

Subsurface Study of Lower Ordovician Prairie du Chien Group and Underlying Cambrian Formations and Their Relation to Pre-Glenwood Unconformity in Southern Peninsula of Michigan: ABSTRACT

Prior to discovery of commercial gas in Lower Ordovician Prairie du Chien sandstones at Falmouth field, Missaukee County, in April 1981, only 119 wells had reached underlying Cambrian rocks in Michigan's Southern Peninsula. The resulting deep basin drilling activity to January 1, 1987, has resulted in 17 Prairie du Chien gas discoveries in the north-central part of the Michigan basin and an additional 46 Cambrian penetrations. This study also utilized 235 Prairie du Chien partial penetrations. It is now possible to correlate with relative certainty the standard Cambrian formations of the subsurface of southern Michigan to wells within and on the other margins of the basin. These, in ascending order, are Mount Simon, Eau Claire, Dresbach, Franconia, and Trempealeau. Because of the previous lack of control, these units were commonly misidentified in northern wells in previous studies. The present study largely corroborates previous recent work. Four ascending formations of the Prairie du Chien Group were also correlated throughout the basin: Umlor, Foster, Bruggers, and Goodwell (newly proposed). Two type wells demonstrate the character of the Goodwell Formation. The Bruggers Sandstones has been further divided into four informal zones, based on extending correlations of thin, silty dolomite marker beds on gamma-raymore » logs from the Goodwell and Woodville fields area, Newaygo County. Gas is produced from these Brugger zones. Twelve detailed stratigraphic cross sections (using 183 wells) and a pre-Glenwood paleogeologic map demonstrate marked basin-wide pre-Middle Ordovician erosional truncation.« less

Thermal Subsidence and Generation of Hydrocarbons in Michigan Basin

Temperature histories for selected stratigraphic horizons in the Michigan basin are computed from three-dimensional continually filled subsidence models. Mechanical evolution of the Michigan basin is modeled as flexure of the lithosphere caused by thermal contraction. Results are compatible with the subsidence record of the sediments and free-air gravity anomalies. Paleotemperature is determined from excess temperature due to the thermal anomaly plus burial temperature predicted from subsidence curves. For an equilibrium temperature gradient of 22°C/km (1.2°F/100 ft), surface temperature of 20°C (68°F), and an equilibrium surface heat flow of 1.1 HFU, excess temperature, paleotemperature, and surface heat flow do not exceed 15°C (27°F), 110 76;C (230°F), and 2.5 HFU, respectively. These estimates are consistent with upper limits set by paleomagnetic studies. The low value for excess temperature is caused by concentration of the thermal anomaly below 15 km (9 mi), in agreement with gravity results. The great depth of the thermal anomaly can explain the lack of evidence for an initial heating event prior to subsidence. Once the thermal history of the sediments is specified, the oil potential of the basin can be determined from laboratory-derived kinetic equations for degradation of kerogen to petroleum. For the Michigan basin, predicted temperature conditions are sufficient for source rock (> 25%) conversion of type I and type II kerogen only in Ordovician and older rocks in the southern peninsula of Michigan. By this model, petroleum found in rocks younger than Ordovician would have had to migrate upward from the older rocks. Geochemical studies of Dundee (Devonian) and Trenton (Ordovician) crude oils in Michigan are compatible with this interpretation. Niagaran (Silurian) crude oils appear to come from a different source than the Dundee and Trenton oils. If their source is Silurian rocks on the flanks of the basin, either the scheme used to calculate maturity is not applicable to these oils or the temperature of the source rocks was significantly higher in the past than today. More likely, the model underestimates the depth of burial of Silurian source rocks near the center of the basin, especially in local regions of downfaulting.

Distribution and Significance of Glacially Buried Organic Matter in Michigan's Southern Peninsula

Within Michigan's Southern Peninsula, the presence of glacially buried Pleistocene organic matter is relatively uncommon but more abundant than previously recognized. These deposits tend to be concentrated in 13 districts and are most closely related to (1) places with high relief on the drift-covered bedrock surface, (2) the extent of buried bedrock valleys, and (3) low areas on a palimpsest paleosurface. Well logs show that multiple organic horizons at any one site are extremely rare, but variations in location, elevation, types of material with their climatic implications, and radiocarbon dates support the conclusion that remnants of several Pleistocene paleosurfaces, preserved through burial by deposits from separate glacial advances, exist at a number of places, especially in the southern part of the peninsula.

Thermal and mechanical evolution of the Michigan Basin

We examine the formation of the Michigan Basin in terms of elastic flexure of the lithosphere. The shape of the flexure accurately determines the flexural rigidity of the lithosphere and the lateral extent of the load responsible for the flexure. The amplitude of differential subsidence then gives the magnitude of the load. Gravity anomalies in the southern peninsula of Michigan further restrain the dimensions of the load. We propose a model for the formation of the Michigan Basin involving mantle diapirs. We suggest that the first stage in its evolution was diapiric penetration of the lithosphere by hot asthenospheric mantle rock to the vicinity of the Moho. The heating of the lower crust by these hot rocks caused the transformation of lower crust, meta-stable gabbroic rocks to eclogite. Initially the lighter mantle rocks nearly balanced the heavier eclogite. As the mantle rocks cooled by conduction, the basin subsided under the load of the eclogite. The thermal contraction mechanism is supported by evidence that the flexural rigidity of the lithosphere increases with time. This is the effect of thickening of the elastic lithosphere as cooling progresses.

Geophysical Studies of Basement Geology of Southern Peninsula of Michigan

Only fragmentary direct information is available on the basement complex of the Southern Peninsula of Michigan because of limited and poorly distributed basement drill holes. This has encouraged the use of geophysical methods, primarily gravity and magnetic, to study the Precambrian formations. A basement configuration map prepared from magnetic depth estimates and basement drill tests confirms that the basement surface under the Southern Peninsula has the form of an oval depression reaching a maximum depth of more than 15,000 ft (4.5 km) below sea level on the western shore of Saginaw Bay. A basement topographic high is associated with the Howell anticline and a roughly north-south-striking basement trough plunges into the basin from the common boundary point of Indiana, Ohio, and Michigan. Aeromagnetic and Bouguer gravity anomaly maps, together with isotopic dates of samples obtained from basement drill holes and extrapolation of known Precambrian geologic trends, indicate that four basement provinces underlie the Southern Peninsula. The Penokean province can be traced geophysically from Lake Michigan into the Southern Peninsula, where it is characterized by east-southeast-striking geophysical anomalies. Central and southwestern Michigan is underlain primarily by felsic rocks correlating with the Central province. Basement rocks in southeastern Michigan strike north-northeast and are interpreted to be metamorphosed intrusive and extrusive rocks and mafic and felsic gneisses of the Grenville province. The Grenville front strikes south-southwest from Sagi aw Bay to west of the Howell anticline and from there due south to the Michigan Ohio boundary. A Keweenawan rift zone characterized by mafic intrusive and extrusive rocks and by uplifted gneisses transects all of the provinces and extends from Grand Traverse Bay to southeastern Michigan. Another subparallel ancient rift zone may be present in southwestern Michigan. These zones were formed during an episode of crustal extension in Keweenawan time. Subsequent deformation of the sedimentary rocks within the basin generally has been associated with movement along lines of basement weakness apparently related to the rift zone and Penokean structural trends.

Design for the Teaching of Landform Geography

Abstract This paper is concerned with an instructional design for the teaching of landform geography. A sequence of organizational problems is examined and suggestions made from a previous study of the southern peninsula of Michigan. Considerations of grid design, selection of terrain parameters, and the problem of regional definitions are assessed from both the historic point of view and the results of the pilot study. Of three basic landform parameters, i.e., average elevations, local relief, and average slope, the single criterion of elevation is advocated for the detection of regional homogeniety over large topographic surfaces. However, the use of local relief as a measure of surface texture is proposed for the delineation of individual terrain compartments. Suggested for all age levels above the elementary school, this project is a feasible design for an oft-neglected aspect of physical geography.

Basement Geology of the Lake Michigan Area from Aeromagnetic Studies

The magnetic field of Lake Michigan is dominated by a series of alternating regional maxima and minima which are, in general, directly related to gravity anomalies on the perimeter of the lake. These magnetic zones are believed to be primarily related to Penokean basement trends which extend from Wisconsin across Lake Michigan into the Southern Peninsula of Michigan. The strike of these zones changes from northeast in southern Wisconsin and east in northern Wisconsin to east and east-southeast respectively in eastern Lake Michigan and Michigan. Exceptions are found in the northern and southern extremities of the lake. In southern Lake Michigan southeast-trending magnetic anomalies are related to a regional gravity high extending across southwestern Michigan into northeastern Indiana. The positive magnetic zone in northern Lake Michigan strikes north from Grand Traverse Bay to north of Beaver Island, where it bifurcates with one limb extending north-northwest through Lake Superior to the Keweenawan basalt on Keweenaw Point. The other limb continues into the eastern portion of the Northern Peninsula of Michigan, and another segment of this branch connects to the Keweenawan flows on Mamianse Point on the eastern shore of Lake Superior. In the Grand Traverse Bay area this positive magnetic zone becomes strongly negative and connects to the south with the mid-Michigan gravity and magnetic anomaly.

Paleogeography of Lower Mississippian Rocks of Michigan Basin

Five Lower Mississippian formations (Antrim, Ellsworth, Bedford, Berea and Sunbury) of Michigan were studied to determine the Early Mississippian paleogeography and to develop an effective and efficient technique for studying thick shale sequences which have variable properties both laterally and vertically. Standardized color descriptions of cuttings from 443 wells throughout the Southern Peninsula of Michigan were the main source of the data, which were later analyzed and plotted by computer techniques. Other variables assessed were thickness, lithologic ratio, and texture. Interpretations based on both intraformational and interformational variations indicate that the factors controlling local deposition became established in the Antrim sea and persisted until the deposition of the Sunbury Shale. The post-Antrim sediments were derived from two source areas northeast and northwest of Michigan. The former produced the birdfoot Bedford-Berea delta, and the northwest source contributed a thick green shale which may represent the prodelta deposits of a delta farther west. The development of these Early Mississippian deltas may be the first indication of greater deltaic sequences in the Pennsylvanian System. The localization of the Bedford-Berea and the Ellsworth rock types on opposite sides of the basin was not effected by a structural or topographic barrier, but by an environment in which all sediments deposited were primarily or secondary black. The organic content of the black shale was preserved in a reducing shallow-water environment. The green shale, however, was deposited in a mildly reducing environment in which the organic matter was not preserved. The green color is due to the abundance of green clay minerals, glauconite, and ferrous ions.

Bottom Sediments of Saginaw Bay, Michigan

ABSTRACT Saginaw Bay is a southwest extension of Lake Huron on the east shore of the Southern Peninsula of Michigan. It is a shallow-water derivative of the Pleistocene Lake Saginaw. Sixty-one bottom samples were collected on a semigrid pattern and analyzed physically. Findings were treated statistically. Sediments range in size from large pebbles to clay. Medium- to fine-grained clear quartz sand is common to all parts of the bay. Currents and wave action are primarily responsible for both median diameter and sorting distribution patterns. Only a very general correlation can be established between depth and median diameter. Heavy minerals occur in abundance locally and show an affinity to shallow-water areas subject to prevailing currents. Shape also locally determines heavy mineral concentra ions. Only general conclusions can be established from roundness and sphericity and acid-soluble content. Increased organic content is correlative with quiet water environments. The shallow-water, heterogeneous nature of Saginaw Bay is not conducive to the recognition of sedimentary criteria suitable for correlations in other than a local environment.

A DENSITY DETERMINATION BY UNDERGROUND GRAVITY MEASUREMENTS IN MICHIGAN

The in situ density of an 1,100‐ft section of Paleozoic sedimentary rocks in the southeastern portion of the Michigan Basin was determined by the established method of observing the change in gravity over a known vertical interval within the earth. The measurements were made in and adjacent to the Detroit Mine (Sec. 33, T2S, R11E) of the International Salt Company in Detroit, Michigan, which is the only deep shaft mine in the Southern Peninsula of Michigan.

Transgressive Marginal Lithotopes in Niagaran (Silurian) of Northern Michigan Basin

Classical stratigraphic studies of the Niagaran of the Michigan basin have all been made in the zone of outcrop, which nearly encircles the southern peninsula of Michigan at the periphery of the basin. Here there is little difficulty establishing equivalency of units, for distinctive faunal and lithologic zones can be traced from Manitoulin Island, Ontario, through the northern peninsula of Michigan and southward into eastern Wisconsin. This has led to the generally accepted stratigraphic interpretation of a succession of Niagaran seas, each with a distinctive environment and the deposits of each separated from those of the preceding and succeeding seas by significant unconformities. With recent drilling information, however, it has become increasingly apparent that the characteristic outcrop zones quickly disappear in the subsurface of Michigan. A detailed examination has been made by the writer of the field relationships of these units on Manitoulin Island which has excellent exposures and which is used as the reference area of this paper. This study has failed to confirm any widespread unconformities above the base of the Niagaran. It is here proposed that the entire Niagaran sequence of the northern rim of the Michigan basin belongs to one large transgressing littoral-lagoon-barrier reef association. Evidence for this hypothesis is seen in the results of insoluble residue analyses made from samples collected at typical Manitoulin Island sections. An unconformity is indicated at the base of the Dyer Bay carbonate unit, which is interpreted as a littoral accumulation of fine carbonate sand deposited at the shoreward edge of the advancing lagoon. The overlying Wingfield and St. Edmund siltstones and calcisiltites reflect the calm, shallow bottom conditions of the lagoon proper, while the Fossil Hill calcarenites and calcirudites were deposited in the higher energy environment of the back-reef detrital zone. The Am bel comprises several facies of the reef core. Overlying the Amabel are detrital beds, formerly mapped as Fossil Hill or its correlatives, which are interpreted as fore-reef detritus, Detritus also occurs in passes through the Amabel reef-core facies.

TRANSPORTATION NETWORK AND URBANIZATION AROUND LANSING, MICHIGAN

The primary object of this study is to analyze the specific character of the American urbanization for which the term “open-country suburbanization”, more specifically “open-country suburban residential development”, could be used, in relation to the transportation network well characterized by the combination of radial and gridiron road patterns. It is the author's hope that some characteristics of American medium-sized cities such as Lansing having nearly a population of 100, 000 within its municipality, and, in addition to that, having also approximately 100, 000 people within the area 35 kilometers from the downtown outside the municipality. The open-country suburban residential development is one of the most significant aspects of the American urbanization at the mid-twentieth century. For a Japanese observer, it is an almost entirely novel experience to see it. Analysis of such a phenomenon might contribute to the understanding of present-day American regional structure at large. Figure 1 shows the general pattern of highways in the southern peninsula of Michigan. Figure 2 illus trates how non-farm residences are located in so-called rural areas. Figure 3 was designed to show thedetail of all public roads together with some other major characteristics of transportation. Figure 4 is the map revealing the urban spread of Lansing, especially its open-country suburban residetial development, in relation to the road network. This map was made by counting the numbers of farmsteads and non-farm residences respectively for each section that appear in the General Highway Maps of Ingham, Eaton, Clinton, Shiawassee, and Ionia Counties. It is quite easy to see that the open-country residences are distributed in all directions almost equally, although there is a general tendency for them to cluster along the major radiating highways. Railroads do not play an important role in the selection of their sites. Notable is the relation of such residential devel-opment to the road network including minor public roads constructed in a gridiron pattern for the most cases according to the General Land Office survey. Figure 5 was constructed by drawing concentric circles around the downtown of Lansing five kilometers apart, and counting the numbers of all farmsteads and non-farm residences respectively for each zone. In order to substitute this diagram, Table 1 was made, in which (A) is the number of non-farm residences and (B) is that of farmsteads. It is worth noting that the non-farm residence ratio decreases until the 20-km, circle, is reached beyond that it levels off. If the 20-km. circle should correspond to the outer limit of urban Lansing, this urban complex would cover 1256 square kilometers. Even if the urban Lansing is limited merely to the area delineated by the 5-km. circle, in which nearly 100, 000 people reside, it covers 80.5 square kilometers. These figures make a sharp contrast to Japanese cities such as Shizuoka having about 200, 000 people within its central urbanized area of slightly over 10 square kilometers. Practically no non-farm suburban residences are found in rural areas outside this compactly urbanized area, although there are many commuters living in farm houses or in urban residences in smaller towns. This kind of immense suburban development is recognized in different parts of the United States of America today where a tremendous urban spread as what Jean Gottmann called Megalopolis or what Allen K. Philbrick has revealed in a map form. This is not an extreme character of American urbainization, but an ordinary or common nature of it. The author wishes to express his sincere thanks to Fulbright Commission for their financial assistance that enabled him to conduct a series of field work in America.

Studies on a Microsporidian Hyperparasite of Strigeoid Trematodes. II. Experimental Transmission

In the first paper of this series (Cort, Hussey and Ameel, 1960) we reported on investigations made during the summers of 1956, 1957, and 1958 on the prevalence and effect on the parasitized larval trematodes of a microsporidian hyperparasite of the genus Nosema, which is found in a large proportion of the strigeoid infections in the snails of the region around the University of Michigan Biological Station near the northern tip of the southern peninsula of Michigan. We also carried out series of experiments designed to solve some of the problems involved in the transmission of this species of Nosema. As in the first paper of this series, we will refer to this microsporidian hyperparasite as Nosema sp. and will not try to determine its exact specific relationships until more details of its life cycle have been worked out. In a preliminary experiment done during the summer of 1956 we tried to find out what happened to the spores of Nosema that were ingested by snails that harbored no trematode infections. Several small laboratory raised juveniles of Physa parkeri were placed in small dishes with enormous numbers of the spores of Nosema sp. They were seen to ingest the spores during the period they were in the dishes with them, so that very large numbers must have entered their digestive tracts. Examinations were made of 2 of these snails, one after 36 hours and the other after 72 hours. Although their tissues were carefully teased apart and examined under the high power of the microscope, no trace of the spores or of anything recognizable as developmental stages of the microsporidian was found. Two more of the snails were killed and fixed for sectioning, one at 36 and the other at 72 hours after exposure to the spores. In examination under high power of the microscope of sections of the whole bodies of these snails no trace of the spores or of anything recognizable as a stage of Nosema sp. was found. Rather late in the summer of 1956 an experiment was performed in which snails harboring larval strigeoids were exposed to very large numbers of the spores of Nosema sp. During the summer of 1957 four more experiments of this same type were carried out, in which it was determined how long it took experimental infections to produce mature spores. In one of these experiments it was demonstrated that the metacercariae (tetracotyles) of Cotylurus flabelliformis could be infected with Nosema sp. Two further experiments in the summer of 1958 showed that the spores could survive at least a year and that several different species of larval strigeoids could be hyperinfected experimentally with this microsporidian.