On July 21, 1913, two steam shovels began excavating the sub-basement at the site of the new Legislative Building. Excavation took 31 days, although seven days were lost because of rain and equipment breakdowns. After five days of excavation, the design plans were modified by, 1) moving the site of the Legislative Building 13 m southward toward the Assiniboine River and away from the main access artery, Broadway Avenue, and 2) raising the terrace adjacent to the building by 0.6 m, and the building by 0.3 m, thus reducing the depth of excavation from 2.5 m to 1.5 m (Manitoba Royal Commission, 1915). Raising the building added an additional 0.3 m of cut stone along the perimeter of the building. During excavation about 16,000 m³ of soil were removed. Some of the excavated soil was probably used to add a raised terrace adjacent to the Legislative Building.

The stratigraphy underlying the Legislative Building was documented in logs from eight test holes sunk in 1912 and 1913 (AM, GR 3085 G8106, Item 176), logs acquired during caisson excavation (AM, GR 3085 G8100, Item 6, AM, GR 3085 G8107, Item 549) and logs acquired during later examination of selected caissons (AM, GR 3085 G8105, Item 121, AM, GR 3085 G8105, Item 122, AM, GR 3085 G8106, Item 196, AM, GR 1609 G8014, File 3 Item 2). This later examination was in response to cracks that developed in the floors and walls of the Legislative Building during construction, particularly along the north outside wall under both wings and the north portico. These logs revealed a stratigraphy consisting of bedrock, commonly overlain by indurated till and unconsolidated boulder clay, overlain by grey and yellow clay and capped by a thin black loam.

The bedrock underlying the Legislative Building consists of carbonate rocks of the lower part of the Fort Garry Member of the Red River Formation (Baracos and Kingerski, 1998). The depth to bedrock is 14 to 15 m from the top of the horizontal steel frame resting on the caissons (i.e., grillage), except under the north part of the building where it occurs at 14 to 20 m (Fig. 5). Bedrock relief in the northeast wing and under the north portico defines abrupt depressions that drop up to several metres (AM, GR 3085 G8106, Item 196, AM, GR 1609 G8014, File 3 Item 2). These depressions in the bedrock surface are consistent with paleokarst features underlying Winnipeg (Baracos and Kingerski, 1998).

Unconsolidated boulder clay or indurated till typically overlies carbonate bedrock (AM, GR 3085 G8100, Item 6, AM, GR 3085 G8105, Item 121) and is probably equivalent to till described by Baracos and Kingerski (1998). Boulder clay underlies most of the Legislative Building, but is absent in the southwest corner of the building whereas the indurated till occurs under the wings of the building, including the northeast wing, but is typically absent under the dome and central part of the building (AM, GR 3085 G8100, Item 6). Where boulder clay and indurated till occur in the same section, the indurated till underlies the boulder clay. Under the northeast wing of the building where depressions occur in the bedrock surface, several metres of silt occur between the bedrock and indurated till (AM, GR 3085 G8107, Item 549).

The boulder clay is overlain by unconsolidated grey clay, generally over-lain by a thinner, yellow clay, which thins to the southwest. The yellow clay also occurs as a discontinuous lens within the grey clay (AM, GR 3085 G8106, Item 176). The grey and yellow clays probably correspond to Agassiz units 1 and 3, respectively (Teller, 1976).

In November 1912, Provincial ArchitectV.W. Horwood suggested a change in foundation design from piles to caissons (Table 2) because of problems with other engineered projects in the Winnipeg area that used piles. The change was implemented in August 1913. Excavation to bedrock of the original 369 caissons (Fig. 5) was started in late August and completed in February 1914 (AM, GR 3085 G8100, Item 6). Under the northeast corner of the building, a caisson intersected up to 3 m of indurated till, but continued excavation never encountered bedrock (AM, GR 3085 G8105, Item 125). To ensure adequate bearing capacity of the indurated till, it was tested once in September 1913 (Fig. 6) and again in October 1913. From this testing, recommendations were adopted that allowed caissons to be taken to indurated till. Recommendations also stated that the indurated till was to be drilled to determine its thickness and the depth to bedrock.

Caissons were dug by hand and the spoil removed in buckets to an overhead railway, which took the clay to carts for disposal. Caisson walls were supported during excavation by wood cribbing held in place by iron rings and bolts (Fig.6). Cribbing in one caisson failed, causing deformation of the walls in five adjacent caisson excavations (AM, GR 3085 G8104, Item 53).

Seepage into caisson excavations from the underlying carbonate aquifer was a common problem. The potentiometric surface of this aquifer underlying much of Winnipeg is currently above the bedrock surface (Render, 1970), and may have been higher at the time of construction. Evidence suggests that most caissons contained some water, and several contained excessive amounts of water when the concrete pour took place (AM GR1609 G8014 File 5, AM GR1609 G8014 File 3 Item 2).

Following the beginning of construction of the first level, cracks appeared in some floors and walls suggesting that some caissons were of poor quality possibly reflecting seepage or that some were installed improperly and had not reached bedrock or induratedtill. (AM, GR 3085 G8102, Item 43). An additional 52 caissons were installed (Fig.5) to replace poor quality caissons, and to repair and underpin caissons that did not reach supporting material (AM, GR 1609 G8014, File 3 Item 1).

Polished grey, pink, and red Tennessee marbles were used throughout the interior of the Legislative Building for room and hallway flooring (Figs. 7g, h, 8a), for steps, risers and landings within enclosed stairwells, for stately cylindrical columns in the second floor rotunda (Fig. 8a), and for drinking fountains (Fig. 7f) on most levels. This stone was used also in the building's public washrooms for partitions and walls.

R. Zurawski, State Geologist and Director of the Tennessee Division of Geology, (pers. comm., 2004), has indicated that this stone came from the Middle Ordovician Holston Formation of the Chickamauga Group. The Holston beds outcrop in the Valley and Ridge fold and thrust belt of eastern Tennessee. The geology of these deposits is described by Gordon (1924).

The stone has a fine- to medium-grained, crystalline texture that has been interpreted as diagenetic. The stone qualifies as a marble in the commercial sense only; it is actually a crystalline limestone that takes a good polish. Small crinoid fragments are embedded in many of the crystalline grains and can be seen in the Legislative Building. Otherwise, stone at the Tennessee quarry sites is reported to contain numerous macro-fossils such as bryozoans, brachiopods, pelecypods and gastropods. These larger forms could not be recognized in the Legislative Building stone.

The Tennessee marble is characterized by well developed stylolites having two orientations. Those parallel to bedding planes are predominant and those oblique to bedding are less common. The stylolites parallel to bedding are well demonstrated in three dimensions in the corridor drinking fountains (Fig. 7f). Stairwell landings reveal unusual structures related to the intersections of the two orientations of stylolites. The origin of these features appears to have involved irregular dissolution and disturbance of bedding, but otherwise is considered problematic.

The variation in colour of the Tennessee stone reflects variations in the amounts of iron oxide. Analyses givenin Gordon (1924), list ferric oxide (Fe2O3) contents in the grey stone as 0.17%; the pink stone as 0.21%; and the deep-red stone as 0.46%.

The Holston beds represent Middle Ordovician carbonate deposition on the North American passive margin of the Iapetus Ocean, an ocean ancestral to the Atlantic Ocean. Scotese (2004) indicates that this area was south of the equator at a latitude of approximately 35° during the Middle Ordovician. These beds were only marginally altered by the Taconic orogenic phase of Appalachian tectonic history (Middle Ordovician-Silurian), but underwent thin-skinned folding and thrusting at a later time during the Late Permian Alleghanian Orogeny (Hatcher, 1987).

Cream- to ivory-Botticino marble from Italy was used in the Legislative Building for the steps and carved railings of the impressive Grand Staircase (Figs. 8a, b), for baseboards and benches in the main entry vestibule and other rooms, for the carved balustrade in the centre of the Rotunda (Fig. 7g), for radiator ledges, for baseboards throughout the building (Figs. 7e, f), and for smooth and carved olive-leaf trim around entrances to offices. This stone also serves as lamp footings in the Pool of the Black Star.

Botticino marble came from Lombardy Province in northern Italy just north of the Po Basin. The stone (also known formerly as Mazzano marble) was quarried close to the city of Brescia, in the foothills of the Southern Alps. It was quarried from selected carbonate beds within the Lower Jurassic, Sinemurian Stage, Corna Formation (Cassinis, 1968). The Corna beds underwent modest folding and thrusting during the early Miocene and these structures verge toward the south and southeast (Schmid, 2003).

The Corna Formation has been described as a fine-grained, compact, allochemical limestone having a veined texture (Italithos, 2004). It has not been metamorphosed and is a marble in the commercial sense only. It contains primary structures described as pseudo-oolites, and also an abundance of fossils including algal masses (oncolites). These features can be observed in the Legislative Building (Fig. 8c). Also reported by Italithos (2004), but more difficult to find in the Legislative Building, are corals, crinoids, sponges, mollusks and forams. Botticino marble has brown stylolites parallel to the bedding (Fig. 8c).

The Corna beds represent shallow marine carbonates, deposited on the eastern flank of the Lombardy Basin in northern Italy, as the basin was in the early stages of its development (Winterer and Bosellini, 1981). The Lombardy Basin represented early Jurassic continental extension that signified the oncoming separation and spreading of the Apulian Plate away from the Eurasian plate, leading to the development of the Ligurian Sea. Subsequent closure of the Ligurian Sea in the early Miocene carried these carbonates into contact with the Alpine orogenic front of the Eurasian Plate, resulting in retro-thrusting and folding (Schmid, 2003).

Black marble was used in the Legislative Building for interior decorative purposes. It was used as floor paving bands and diamonds throughout the Legislative Building on the main and second floors (Figs. 7g, h, 8a) and also in the Legislative Chamber at the bases of walls, and as ceremonial pedestals on both sides of the Speaker's platform (Fig. 8f). This stone is a marble in the commercial sense only. Actually, it is a black, fine-grained limestone that takes an excellent polish and contrasts with the white macrofossils that are scattered throughout the stone or concentrated in layers; these are most obvious in the Legislative Chamber, but they can also be seen in the floors.

There is uncertainty about the source of this stone. It likely came from Isle La Motte in Lake Champlain, on the Vermont side of the border with New York. In this case the source quarry may have been one of five old quarries on the island that produced a stone called Champlain Black (M.J. Gale, Vermont Geological Survey, pers. comm. 2004). Champlain Black, the North American black marble most widely used in the first part of the twentieth century, was derived from the Crown Point Formation of the Middle Ordovician (Whiterockian) Chazy Group (Norton, 1993). The Crown Point Formation is mostly composed of muddy limestones to calcarenites, with local reefal facies (Oxley and Kay, 1959).

In the black marble, the most abundant fossils are crinoid stem segments, but there are also brachiopods, bryozoans, stromatoporoids, cephalopods, gastropods, and corals (Fig. 10a-d). These are similar to forms found in the Crown Point Formation and other Chazyan units. The fossil assemblage includes stromatoporoids similar to the Crown Point Formation's Labechia and Pachystylostroma (Kapp and Stearn, 1975), and examples of the coral genus Foerstephyllum consistent with F. wissleri (Welby, 1961), which occurs in blue-black limestones of the Crown Point Formation in the Lake Champlain area. Nevertheless, we have not been able to identify the most characteristic Crown Point fossil, the gastropod Maclurites magnus (Oxley and Kay, 1959). Consequently the Legislative Building stone could have been derived from some other mid-Ordovician unit, but likely from the New York – Vermont area.

The Chazy Group was deposited on a passive North American continental margin as the Iapetus Ocean was undergoing closure. It represents a range of environments from storm-dominated shelf to sand shoals and tidal flats (Mehrtens and Selleck, 2002). The beds were deposited during or shortly after a period of block faulting (Mehrtens and Selleck, 2002), and were deformed into open folds during the Appalachian Taconic Orogeny.

Butler granite is a grey gneissic granite that was used for the steps and landings of the four exterior porticos of the Legislative Building (Figs. 7a, d). The granite came from the Horne Quarry, near Ignace, Ontario, now known as the Butler Quarry that is located in Bradshaw Township, District of Kenora, 7.7 km west of the town of Ignace on the north side of Highway 17, adjacent to the Canadian Pacific Railway right of way.

Storey (1986) indicates that the rock is a massive, light grey to white, biotite granite (approximately 5% biotite). A very weak foliation trends north-northwest. There are no obvious knots or inclusions in the granite but there are rare rusty-weathering spots on the weathered surface. The rock polishes well with no plucking of the biotite. The major joint set in the granite strikes Az 110°, with minor sets at 045° and 070°. The stone on the Legislative Building porticos is characterized by local variations in composition and grain size resulting in a layered gneissosity, along with patches of pegmatite.

Mineral point count analysis identifies the predominant phase of this rock as a quartz monzonite. The mineralogy is 40% plagioclase (3% of which is myrmekitic), 29% quartz, 28% potassium feldspar (microcline and orthoclase), 3% biotite, with trace magnetite and rare epidote and chlorite.

The Butler granite represents part of the Indian Lake batholith (Blackburn et al., 1991), one of many granitoid plutonic complexes that occur within the central Wabigoon Subprovince, of the Superior Province of the Canadian Shield. Two U-Pb zircon crystallization ages for the batholith are both 2671 Ma (Tomlinson et al., 2004). These ages are the youngest within the central Wabigoon Subprovince and suggest that the pluton may be a product of post-collision continental magma generation following earlier Archean continental plate growth as described by Blackburn (1980). The Butler granite represents the oldest dimension stone used in the Legislative Building.

Bedford limestone was used for most of the statuary of the Legislative Building (Fig 7a). Decades of weathering have developed some inter-granular relief on the surfaces of the exterior carved works (Fig.7b). The Bedford limestone now is formally known as Salem Limestone, but also simply as Indiana limestone. It was quarried in south-central Indiana, between Bloomington and Bedford. It has been used as a dimension stone for over 100 years because of its uniform texture and ease of working. It is fairly soft and can be shaped easily with carving tools.

The limestone is described as a cross bedded calcarenite that is medium-to coarse-grained, tan, grey tan, and light grey, porous, and fairly well sorted. It occurs in exceptionally thick beds. Individual grains are mostly microfossils (including especially the foraminiferid Globoendothyra baileyi), macrofossil fragments, and whole diminutive forms of macrofossils. Coated grains and oolitic textures are also common (Indiana Geological Survey, 1997; Pinsak, 1957).

The stone was deposited in an epi-continental, warm-water, marine environment during Mississippian time. The fine-grained oolitic texture suggests that wave action and marine currents winnowed the fossil fragments to a uniform size (Ketter, 2003). The Indiana Geological Survey (1997) classifies this stone as chemically pure, averaging 97 % plus calcium carbonate and 1.2 % calcium-magnesium carbonate.

Vermont Verde Antique is a serpentine marble that has irregularly mixed green chlorite and intermediate to dark green serpentine, irregularly veined with white calcite. It was used for a variety of decorative purposes in the Legislative Building to provide artistic contrast with the lighter coloured Tennessee and Botticino marbles. (Figs. 7g, h). Examples include the patterned floors of the Grand Staircase hall, the Pool of the Black Star, the Rotunda, and the Manitoba Room on the second floor. Verde Antique was used also as fireplace trim in the Speaker's offices.

This marble came from one of several serpentinite bodies near the town of Roxbury, Vermont. M. J. Gale, Geologist, Vermont Geological Survey (pers. comm. 2004) has indicated that several quarries there operated from 1853 through to the 1950s. The serpentinite occurs as pods and lenses in the Missisquoi Formation, a metamorphic complex in Vermont assigned to the Lower Ordovician. Structurally, these rocks occur on the eastern limb of the Green Mountain Anticlinorium.

The structural setting, composition, and pod-like form of the source serpentinite bodies have led to the interpretation that the original ultramafic material represents the pre-Taconic oceanic crust (possibly ophiolite) flooring the Iapetus Ocean. The bodies may represent dismembered, complexly sheared and metamorphosed material caught up in an accretionary wedge during the Appalachian Taconic Orogeny (Williams, 1984).

Missisquoi marble (Fig. 8g) was used as flooring in parts of the northern upper-level corridors of the Legislative Building. The stone was described by Parks (1914) as having characteristic colour variations consisting of shades of light and dark grey, sometimes arranged in irregular patterns. The patterns were commonly described as ovoid in form, up to 20 cm across, and locally separated by green stylolites.

The Missisquoi marble comes from quarries at Philipsburg, Québec. The stone occurs in beds of the upper member of the Late Cambrian to Early Ordovician Strites Pond Formation (Salad Hersi et al., 2002). Salad Hersi and Lavoie (2001, p.8) indicate that one upper limestone lithofacies of the Strites Pond Formation is composed of crystalline limestone " … characterized by small, irregularly woven, light grey and medium grey patches of dense micrite, which gives a mottled appearance similar to clotted bioherms. Looking from the bedding surface, these bioherms form rounded, ellipsoidal, and irregular mounds with stylolitic boundaries". This description is consistent with the stone in the floors within the alcoves at the two ends of the upper-level north hall, which has the appearance of domical stromatolites that have been cut parallel to bedding (Fig. 8g). Otherwise the Missisquoi marble used on the floors of the upper level is of the non-patterned, light grey type.

The attributes of the upper Strites Pond Formation suggest sedimentation in a subtidal to supratidal setting on the North American passive margin during the Late Cambrian to Early Ordovician; the formation was subsequently slightly deformed and metamorphosed to low-greenschist grade during the Taconic Orogeny (Salad Hersi et al., 2002).

This colourful stone was used exclusively as fireplace trim in meeting rooms and in most Ministers' offices (Figs. 8d, e). Records show that the original stone specified for fireplace trim was black marble, and that a later cost-saving substitute was to have been one of several possibilities (AM, GR 1609 G8015, File 4, report on deductions and alterations), none of which was used.

Macroscopic examination of this red marble was restricted to properties that could be observed on polished faces around the fireplaces, because it was not possible to extract samples for microscopic or laboratory analysis. The rock is calcareous, and macroscopic structures and textures indicate a history of fragmentation followed by lithification. Most fragments are angular. Larger fragments are grey, buff, or rose and may contain white calcite veins, and commonly have darker red alteration rims. The matrix consists of smaller fragments or fine-grained material having an orange-rose to deep-red colour. No layering or stratification was discerned from the polished surfaces, and no preferred orientation of long dimensions of fragments was identified. The available evidence suggests the possibility of karst dissolution, collapse and brecciation, followed by lithification. As far as can be determined from textural evidence this stone may be a marble in name only.

No other relevant archival material has been located concerning the source of this stone. A recent search of commercial stone products has yielded one stone from Picardy Province in France, named Brèche St. Maximin that is similar to the red marble breccia. Notwithstanding, the evidence is not compelling; consequently we use a generic name and acknowledge that the age, geological setting and origin of this stone are uncertain.

Bird's Hill, 10 km northeast of Winnipeg, was the source of almost all aggregate used in the construction of the Legislative Building (AM, GR 1609 G8016, File 9). The first development of the Bird's Hill gravel and sand deposit took place in the 1890s, and production continues to this day. During construction of the Legislative Building, sand and gravel were transported to the city by train using a special spur line of either the Winnipeg Selkirk & Lake Winnipeg Railway Company, or the Canadian Pacific Railway.

The Bird's Hill deposit is an esker-delta complex approximately 15 km in length. It consists of coarse-grained, braided, esker deposits near the western margin, changing to finer deltaic deposits to the east. It is surrounded by silt and clay deposits of glacial Lake Agassiz. Nielsen and Matile (1982) stated that the complex was formed at a retreating ice margin approximately 12,000 years ago. Melt-water carried glacially-derived sediment from two ice margin crevasses into Lake Agassiz and produced the esker-delta complex. Subaqueous mass wasting, wave action from Lake Agassiz, and subaerial erosion modified the original distribution of material.

Approximately ten million bricks were used in the construction of the Legislative Building (Manitoba Royal Commission, 1915). They were used for construction of load bearing walls (piers) on all levels and usually were faced with dimension stone or plaster. Unadorned piers can be observed in service corridors and some storage rooms in the basement, and in service areas above the second floor. Brick piers also were constructed on higher levels to support the dome of the Legislative Building. Two types of brick were used, one buff coloured and the other red. They were manufactured from local materials by two Manitoba brick plants between 1913 and 1916.

Most of the bricks are buff coloured and came from the Stephens Brick Company in Portage la Prairie, Manitoba (AM, GR 1609 G8014, File2).The source for the Stephens bricks was postglacial alluvial clay, yellow-grey in colour, that filled abandoned channels of the Assiniboine River near Portage la Prairie, Manitoba. The clay in the channels is 1.5 to 2.7 m thick and is overlain by approximately 0.5 m of soil (Bannatyne, 1970). The Stephens bricks were molded by the soft-mud press process, then dried for eight to ten days, after which they were fired to a buff or pale brown.

The red bricks came from a plant operated by the Leary-Alsip Brick Company in Roseisle, Manitoba. Archival material supporting this source was less definite; consequently X-ray analysis was conducted to confirm Leary-Alsip as the manufacturer. Leary-Alsip bricks contain quartz, microcline and muscovite in contrast with the Stephen bricks, which contain diopside and quartz. The source of the Leary-Alsip bricks was the Cretaceous Morden Shale (McNeil and Caldwell, 1981) that is dark and carbonaceous. The Morden Shale was quarried along the Pembina Hills part of the Manitoba Escarpment, from the banks of Roseisle Creek. After crushing and sieving the shale was formed into bricks by a dry press process. The bricks were fired to their typical red colour in a down-draft beehive kiln (Bannatyne, 1970). These bricks were admired by the architect, Frank W. Simon, for their superior strength. (AM, GR 1609 G8014, File 2). The Leary kiln stands today.

Chemical analyses and temperature gradient tests relevant to the manufacturing of both types of brick are given by Bannatyne (1970).