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CROSS REFERENCE  
       [0001]    This application is a division of U.S. patent application Ser. No. 10/033,460, which is a continuation-in-part of U.S. patent application Ser. No. 09/811,119 filed Mar. 17, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 09/377,094 filed on Sep. 19, 1999, now U.S. Pat. No. 6,250,850. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to retaining walls. More particularly, the present invention relates to manufactured blocks that are used to construct mortarless retaining walls.  
         BACKGROUND OF THE INVENTION  
         [0003]    Retaining walls can be both functional and decorative and range from small gardening applications to large-scale construction. Such walls are typically used to maximize horizontal surface areas by providing lateral support between differing ground levels, and reduce the possibility of erosion and slumping. They may be constructed of a variety of materials and shapes. Some have been constructed of wood timbers, others of rock in a natural form (such as limestone). Still others have been constructed of manufactured aggregate or concrete blocks.  
           [0004]    Constructing a fit and true retaining wall can be a more labor intensive and exacting endeavor than one would believe. In addition to laying a level first course, the builder must take pains to ensure that each subsequent course is level. Otherwise, an error made in positioning a block in a lower course may become magnified as successive courses are stacked thereabove and become readily apparent to the human eye. This is especially true of mortarless wall constructions because there is no way to effectively compensate for irregularities and discontinuities, as opposed to block and mortar construction.  
           [0005]    Present mortarless wall building methods usually include laying a course of blocks, filling the space behind the course with fill material, packing the fill material, and carefully removing extraneous fill material from the top of each completed course prior to the addition of the next course. This fill material usually consists of small, stones or similar material and is preferred because it provides a path for moisture to follow and relieves water pressure that may build up behind a wall. It is also preferred because of its ability to reduce water borne material from seeping between the joints of the blocks due to inclement weather. The final step of removing the extraneous fill material is time consuming but necessary to ensure the next course of blocks lies flat in intimate contact on the lower course.  
           [0006]    One particular problem the prior art has failed to overcome is developing a retaining wall block configured to minimize or prevent unintended discontinuities and irregularities caused by blocks being stacked on extraneous fill material, dirt, and debris that is often present on the upper surface of the lower course of blocks.  
           [0007]    For example, some larger blocks incorporate through-holes that extend from their bottom surface to their top surfaces. These through-holes are intended to reduce the amount of material required to form the block, thereby reducing its cost and weight, and they also create space into which fill material may be introduced once a course is finished. At first blush it would appear that, because the presence of through-holes reduces the surface area of the top and bottom of the block, they would also serve to decrease the area of possible interference by small stones and debris between courses. However, the mere presence of through-holes ensures the chances that some of the fill material dumped therein will spill over onto the remaining upper surfaces. Thus, through-holes actually exacerbate, rather than alleviate the problem.  
           [0008]    Smaller blocks, on the other hand, cannot easily incorporate through-holes without jeopardizing their structural integrity, and this inability of smaller blocks to accommodate through-holes creates other problems. Fabricating a solid block out of material such as concrete may often result in a block which may weigh as much as or more than a larger block that includes through-holes. And, working with such blocks may be more difficult than working with larger blocks with through-holes. That is, the absence of through-holes or interruptions in the side walls makes it difficult to grasp and lift these blocks. This becomes an important consideration in light of the number of blocks that must be lifted and set in place during the construction of even a relatively small retaining wall.  
           [0009]    There is a need for a retaining wall block, which may accommodate debris between courses without adversely affecting the overall structure and aesthetics of the resulting wall. There is also a need for a small retaining wall block that has a reduced unit weight due to the absence of block material in an area that will not adversely affect the strength of the block or its appearance. And, there is a need for a small retaining wall block that is relatively easy to grasp and pick up off of a stack of similar blocks.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention relates to a retaining wall block so shaped that when placed on top of a lower course of similar blocks, it lies flat despite the inevitable presence of dirt, small stones, and other debris. This feature alleviates the time-consuming step of meticulously cleaning the top of each course of blocks before the next course may be laid on top of it.  
           [0011]    In order to achieve the tolerance of small stones and debris between courses, a portion of the bottom surface of the block of the present invention is non-planar, and preferably, concave. This non-planar portion significantly reduces the area for block-to-block contact between successive courses. It also functions to provide an area of clearance or a gap between adjacent blocks where debris can migrate without causing interference or instability between courses. The non-planar portion may be curved, preferably in the shape of a portion of a cylinder and extends from one side surface to the other. Alternatively, the non-planar portion could be shaped to form a portion of a sphere, oval, or any other shape that is capable of tolerating small stones and debris between courses. Preferably, the non-planar portion covers more than one half of the area of the bottom surface of the block.  
           [0012]    In addition to the non-planar portion of the bottom surface, the present invention further comprises a plurality of grooves formed in the bottom surface and extending substantially transversely thereacross, preferably in parallel between the front and back surfaces. The grooves preferably are angled upwardly to form an inverted “V” shape when the block is given its intended orientation. The grooves allow spaces of increased clearance for larger stones. The grooves preferably comprise two opposed surfaces of a predetermined width and which are angled to form a “V” shape and meet to form an angle α. The angled walls of the grooves not only reduce the weight of the block and act as a splitting aid, but also act to direct larger stones into the grooves, thereby positioning them into an area of maximum clearance. Alternatively, the first and second surfaces may be joined by a third, curved or flat, surface juxtaposed between the first and second surfaces. Such a third surface would give the groove an inverted “U” shape. Preferably the grooves are integrally formed with the block and have a predetermined depth, which more or less follows the contour of the non-planar bottom surface.  
           [0013]    The bottom surface further comprises one or more downward projections proximate the rear surface and having an abutting surface which contacts the rear surface of a lower course of blocks when the block is stacked thereon. It is envisioned that the abutting surface is either parallel to the rear surface of the block, or forms an angle β with the rear surface. These projections create an automatic and uniform setback among successive courses of blocks so that the resulting retaining wall is angled rearwardly. This also adds resistive strength to the wall against the natural forces exerted on the wall by the earth the wall is retaining, by tying successive courses of blocks to those course below them.  
           [0014]    In an alternative embodiment, the block generally comprises a substantially continuous top surface, front and back surfaces extending from the top surface, multi-faceted side surfaces extending from the top surface and spanning from the front surface to perpendicularly intersect the back surface, and a bottom surface having a predetermined surface area that is integral with the front and side surfaces. An upwardly extending gutter is formed into the bottom surface of the block and is spaced away from the rear surface of the block a predetermined distance. The gutter formed into the bottom surface of the block preferably has a forward edge that has a minimal surface area that acts to support a rear portion of the block upon a lower course of blocks.  
           [0015]    In order to further lighten a block constructed according this embodiment, the multifaceted side surfaces of the blocks include an inwardly inset sidewall portion that perpendicularly intersects the rear surface of the block. The multifaceted side surfaces of the block may further comprise a shoulder formed between the aforementioned sidewalls and a forward portion of the multifaceted side surfaces wherein the shoulder and the forward portion of the multifaceted side wall intersect at an obtuse angle.  
           [0016]    Preferably, the downward projection has a generally trapezoidal cross-sectional shape and is spaced away from the rear surface of the block a predetermined distance. In addition, the abutting surface of the downward projection is preferably contiguous with a rear face of the gutter.  
           [0017]    The front surface of the aforementioned preferred embodiments may be configured to have a plurality of planar segments or may be curvilinear. However, it is understood that other configurations are possible. For example, the front surface may be planar, angular, or prismatic and have a wide variety of finishes.  
           [0018]    The present invention advantageously provides a block for use in building a retaining wall that produces a level course of blocks, despite the presence of a small amount of debris on the lower course of blocks.  
           [0019]    The present invention is also advantageous in that it provides a relatively small block with material removed from strategic locations to provide a block which is lighter than it would have been had it been solid, yet the removal of material has not adversely affected the strength of the block, nor the appearance of the resulting wall.  
           [0020]    The present invention advantageously provides a block that has areas for a person building a retaining wall to grasp the block when lifting the block off of a stack of such blocks and placing the block on a lower course of blocks in the wall being constructed.  
           [0021]    These and other objectives and advantages of the invention will appear more fully from the following description, made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a perspective view of a block of the present invention, looking up at the bottom to reveal the details of the bottom surface;  
         [0023]    [0023]FIG. 2 is a cross sectional view of the block of the present invention taken along lines  2 - 2  of FIG. 1;  
         [0024]    [0024]FIG. 3 is a cross sectional view of the block of the present invention taken along lines  3 - 3  of FIG. 1 and shown with other blocks in phantom, stacked, as in a retaining wall;  
         [0025]    [0025]FIG. 4 is a bottom plan view of the block of FIG. 1;  
         [0026]    [0026]FIG. 5 is a perspective view of the block shown in FIG. 1 in a stacked relationship with other blocks, as in a wall, and showing debris resting on a lower course of blocks and accommodated for by the concave area of the bottom surface of the block of the present invention;  
         [0027]    [0027]FIG. 6 is a perspective view of an alternative embodiment of the present invention, looking up at the bottom to show the detail of the bottom surface;  
         [0028]    [0028]FIG. 7 is a sectional elevational view taken along lines  7 - 7  of FIG. 6;  
         [0029]    [0029]FIG. 8 is an end elevational view of a block of the embodiment shown in FIG. 6, in stacked relation, as in a wall, with other blocks shown in phantom;  
         [0030]    [0030]FIG. 9 is a bottom plan view of a block of the embodiment shown in FIG. 6;  
         [0031]    [0031]FIG. 10 is a bottom plan view of a block of the present invention;  
         [0032]    [0032]FIG. 11 is a cross-sectional view of the block of FIG. 10 taken along cutting lines  11 - 11  in FIG. 10;  
         [0033]    [0033]FIG. 12 is a cross-sectional view of the block of FIG. 10 taken along cutting lines  12 - 12  in FIG. 10;  
         [0034]    [0034]FIG. 13 is a top plan view of the block of FIG. 10;  
         [0035]    [0035]FIG. 14 is a front elevational view of the block of FIG. 10;  
         [0036]    [0036]FIG. 15 is a side elevational view of a first side of the block of FIG. 10;  
         [0037]    [0037]FIG. 16 is a side elevation view of a second side of the block of FIG. 10;  
         [0038]    [0038]FIG. 17 is a perspective view of an alternative embodiment of the block shown in FIG. 1 in a stacked relationship with other blocks, as in a wall, and showing debris resting on a lower course of blocks and accommodated for by the non-planar area of the bottom surface of the block of the present invention and also showing a curved front surface;  
         [0039]    [0039]FIG. 18 is a perspective view of an alternative embodiment of the present invention, looking up at the bottom to show the detail of the bottom surface;  
         [0040]    [0040]FIG. 19 is a bottom plan view of a block of the embodiment shown in FIG. 18;  
         [0041]    [0041]FIG. 20 is a bottom plan view of an alternative embodiment of the block of the present invention in which the front surface is curved;  
         [0042]    [0042]FIG. 21 is a top plan view of the block of FIG. 20;  
         [0043]    [0043]FIG. 22 is a front elevation view of the block of FIG. 20; and, FIG. 23 is a side elevation view of a series of blocks of FIG. 20 as they would appear in a stacked relation. 
     
    
     DETAILED DESCRIPTION  
       [0044]    Referring now to FIG. 1, there is shown a retaining wall block  10  having a front surface  12 , side surfaces  14   a  and  14   b  extending rearwardly from front surface  12  and integral with rear surface  16 . Top surface  18  is generally planar and continuous across its extents. Top surface  18  extends from side surface  14   a  to side surface  14   b,  and from front surface  12  to rear surface  16 . Preferably, top surface  18  is generally perpendicular to side surfaces  14   a  and  14   b,  and also to front surface  12  and rear surface  16 .  
         [0045]    In the embodiment shown in FIGS.  1 - 9 , front surface  12  comprises three parts,  12   a,    12   b,  and  12   c.  Part  12   c  is generally parallel to rear surface  16  and lies between parts  12   a  and  12   b.  Parts  12   a  and  12   b  are angled such that they extend from part  12   c  and diverge rearwardly to meet side surfaces  14   a  and  14   b,  respectively. Parts  12   a,    12   b,  and  12   c  are shown as split faces as opposed to formed or finished faces. Creating a face with a rock splitter results in an irregular, more natural appearing surface. Also shown in the Figures is a rear surface  16  that has a smaller width than front surface  12  such that side surface  14   a  and  14   b  must converge rearwardly in order to be integral with rear surface  16 . This shape allows the construction of straight, concave, convex, or serpentine walls without interrupting the relatively uniform appearance created by the front surfaces  12  of a plurality of blocks  10  forming a wall.  
         [0046]    Bottom surface  20  extends from front surface  12  to rear surface  16  and from side surface  14   a  to side surface  14   b.  Bottom surface  20  includes a non-planar portion  22 . Non-planar portion  22  is depicted in FIGS. 1, 3, and  4  as a relatively cylindrical indentation in bottom surface  20 , extending from side surface  14   a  to side surface  14   b.  The non-planar portion  22  does not intersect the front surface  12 , and preferably does not extend substantially forward of the intersection where side surfaces  14   a  and  14   b  meet parts  12   a  and  12   b  of front surface  12 . This ensures that non-planar portion  22  is substantially hidden from view in a completed wall, regardless of whether the wall is straight, concave, convex, or serpentine.  
         [0047]    Allowing non-planar portion  22  to extend from side surface  14   a  to side surface  14   b  creates a gap  24  between the bottom surface  20  and the upper surface of a lower course of blocks when block  10  is placed thereon. This gap  24  may be used for ease in picking the block up and setting the block down. Also, as shown in FIGS. 1, 3 and  4 , non-planar portion  22  extends rearwardly but ends forward of downward projection  34 , which is described in more detail below. Ending the non-planar portion  22  forward of downward projection  34  provides another flat surface for block-to-block contact to assist in the leveling and stabilization of block  10  on a lower course of blocks.  
         [0048]    Alternatively, it is envisioned that non-planar portion  22  be an indentation of any shape, such as the generally ovate or spherical shape of the embodiment shown in FIGS.  6 - 9 . Preferably, non-planar portion  22  is large enough to occupy at least  30  percent, more preferably on the order of 50 to 75 percent, of the surface area of bottom surface  20 .  
         [0049]    In one embodiment, bottom surface  20  also includes at least one, preferably a plurality of, grooves  28 . As shown in FIG. 2, grooves  28  are preferably “V”-shaped and extend from the bottom surface into the block toward top surface  18 . In the embodiment depicted in FIGS. 1 and 2, grooves  28  are spaced generally equidistant from each other and oriented such that they extend from front to back generally across the non-planar portion  22 . It is envisioned that grooves  28  could be located generally anywhere across bottom surface  20 . It is preferred, however, that grooves  28  do not intersect front surface  12  so that grooves  28  remain hidden from view when block  10  is part of a completed wall.  
         [0050]    Grooves  28  having the preferred “V” shape generally comprise at least a first surface  30  and a second surface  32 . First surface  30  extends from bottom surface  20  and is integral with second surface  32 . Second surface  32  extends from first surface  30  to bottom surface  20  thereby forming an angle α between first surface  30  and second surface  32  as seen in FIGS. 2 and 7. Angle α is preferably less than 180 degrees. Alternatively, first surface  30  and second surface  32  could be joined by a third surface (not shown in the Figures), which extends along the length of the groove and is juxtaposed between the first and second surfaces. This third surface could be curved, thereby forming a “U” shaped groove, or the third surface could be flat, thereby forming a rectangular groove. However, a “V” shaped groove generally eases manufacturing.  
         [0051]    As shown in all Figures, bottom surface  20  also includes at least one downward projection  34 . Downward projection  34  may extend across bottom surface  20 , adjacent rear surface  16  as shown in FIGS. 1, 2, and  4 . Alternatively, projection  34  may be broken into more than one projection  34  as shown in FIGS. 6, 7 and  9 . Projection  34  has an abutting surface  36  which is used to abut against the rear surface  16  of a lower course of blocks, thereby forming a setback between successive courses of blocks. This setback adds strength and stability to the resulting wall.  
         [0052]    Abutting surface  36  may be substantially parallel to rear surface  16 . Alternatively, for ease of manufacture, abutting surface  36  may angle rearwardly forming a relatively small angle β with rear surface  16  as shown in FIG. 3. Angle β is preferably less than 45 degrees, more preferably less than 30 degrees. A smaller angle β provides more resistance to horizontal block slippage due to external forces against the back of the resulting wall.  
         [0053]    Referring now to FIGS.  10 - 16 , there is shown a preferred embodiment of a retaining wall block  50  having a front surface  52 , side surfaces  54   a  and  54   b  extending rearwardly from front surface  52  toward rear surface  56 . Top surface  58  is generally planar and continuous across its extents. Top surface  58  extends from side surface  54   a  to side surface  54   b,  and from front surface  52  to rear surface  56 . Preferably, top surface  58  is generally perpendicular to side surfaces  54   a  and  54   b,  and also to front surface  52  and rear surface  56 .  
         [0054]    In the embodiment shown in FIGS.  10 - 16 , front surface  52  comprises three parts,  52   a,    52   b,  and  52   c.  In general, these parts will referred to as the front surface parts or as the face of the block  50 . Part  52   c  is generally parallel to rear surface  56  and lies between parts  52   a  and  52   b.  Parts  52   a  and  52   b  are angled such that they extend from part  52   c  and diverge rearwardly to meet side surfaces  54   a  and  54   b,  respectively. Parts  52   a,    52   b,  and  52   c  are in FIGS.  10 - 16  shown as formed or smooth faces as opposed to split faces. Block  50  may preferably be formed by splitting as described above in conjunction with FIGS.  1 - 9 . Creating a face with a rock splitter results in an irregular, more natural appearing surface. As can be seen in the Figures, rear surface  56  has a smaller width than front surface  52 . Side surfaces  54   a  and  54   b  converge rearwardly toward the rear surface  56  at obtuse angle to the rear surface  56 . This shape allows the construction of straight, concave, convex, or serpentine walls without interrupting the relatively uniform appearance created by the front surfaces  52  of a plurality of blocks  10  forming a wall.  
         [0055]    Block  50  has a heel portion  70  that comprises the rear surface  56 , a projection  72 , and a gutter  74 . As can be seen most clearly in FIGS. 10 and 13, sides  54   a  and  54   b  incorporate shoulders  76   a  and  76   b,  respectively. Shoulders  76  may also be seen as a forward boundary of the heel portion  70  of the block  50 . Note that shoulders  76  form an obtuse angle with respect to sides  54 . Heel portion side walls  78   a  and  78   b  extend rearwardly from respective shoulders  76   a  and  76   b  and intersect with rear surface  56  of block  50 . Heel portion side walls  78   a  and  78   b  are preferably formed perpendicular to shoulders  76   a  and  76   b  and to rear surface  56  of block  50 . The resulting sides  54  comprise multiple facets and provide a number of benefits. Formation of side walls  78   a  and  78   b  as illustrated in the Figures results in a lighter block  50  as the block  50  will have a smaller volume. As a corollary benefit, less concrete material is used in the formation of block  50  where side walls  78   a  and  78   b  are formed as indicated.  
         [0056]    Bottom surface  60  extends from front surface  52  to gutter  74  and from side surface  54   a  to side surface  54   b.  Bottom surface  60  includes a non-planar portion  62 . Non-planar portion  62  is depicted in FIGS. 11, 12,  15 , and  16  as a relatively cylindrical indentation in bottom surface  60 , extending from side surface  54   a  to side surface  54   b.  Preferably, non-planar portion  62  does not extend substantially forward of where side surfaces  54   a  and  54   b  intersect parts  52   a  and  52   b  of front surface  52 . In this way non-planar portion  62  will be substantially hidden from view in a completed wall, regardless of whether the wall is straight, concave, convex, or serpentine.  
         [0057]    Allowing non-planar portion  62  to extend from side surface  54   a  to side surface  54   b  creates a gap  64  between the bottom surface  60  and the upper surface of a lower course of blocks when block  50  is placed thereon. This gap  64  may be used for ease in picking the block  50  up and setting the block down. As can be seen in FIGS. 11, 12,  15 , and  16 , gap  64  extends all the way to the edge  75  of gutter  74 . Because gap  64  extends all the way to edge  75  of gutter  74 , a block  50  in an upper course of blocks will rest upon a block  50  in a lower course of blocks upon that portion of bottom surface  60  that extends between the front face parts  52   a,    52   b,  and  52   c  and the forward edge  63  of the non-planar portion  62  and the edge  75  of gutter  74 . As can be appreciated, the rear of the block  50  is supported only on edge  75  and not on a planar surface, i.e. edge  75 , while having any number of curvilinear and/or rectilinear shapes, has a small surface area with respect to the remainder of bottom surface  60 . This affords the benefits of increased friction between two courses of blocks  50  and prevents the entrapment of sand, gravel, or bits of concrete between the upper surface  58  of a lower course of blocks and the bottom surface  60  of an upper course of blocks.  
         [0058]    Gutter  74  extends upwardly from edge  75  into the body of block  50  toward the top surface  58 . Gutter  76  extends laterally between heel portion side walls  78   a  and  78   b  and has a generally “U” shaped cross-sectional area. Note that the exact cross-sectional shape of the gutter  76  may vary. However it is important to form the gutter  74  without sharp-edged surfaces. Therefore, the cross-sectional shape of the gutter  74  will be gently curved within the constraints of its position and size. Such a shape avoids the formation of unwanted stress concentration points that might facilitate the fracture of the block.  
         [0059]    The rear face of the gutter  74  extends downwardly, away from the top surface of block  50  and beyond edge  75  to form an abutting surface  80  of projection  72 . Projection  72  and its abutting surface  80  function in the same manner as projection  34  and its abutting surface  36 , described above. That is, projection  72  acts to rearwardly offset each course of blocks  50  from the lower course upon which the upper course of blocks  50  rest. Projection  72  is preferably offset forwardly from the rear surface  56 . As can be seen in the Figures, rear face  82  of projection  72  is moved forward of the rear surface  56  of the block  50 . Additionally, it is preferred to cant the rear face  82  of projection  72  forwardly so that the projection has a generally trapezoidal cross-sectional shape with radiused edges. While this trapezoidal shape is not the only shape that may be used, it does afford additional durability to the projection  72  in that the lack of sharp edges prevents chipping and fracture of the projection  72 . The trapezoidal shape of the abutting surface  80  of the projection  72  aids in the rapid construction of walls by preventing the entrapment of sand, gravel, or pieces of concrete between the abutting surface  80  of the projection  72  of a block  50  in an upper course and the rear surface  56  a block  50  in a lower course.  
         [0060]    The formation of a heel structure  70  such as that illustrated in FIGS.  10 - 16  has the additional benefit of strengthening the projection  72  by forcing more of the concrete from which the blocks  50  are formed into the area of the mold that forms the projection  72 . Projection  72  of block  50  therefore has fewer voids, is more dense and is consequently stronger.  
         [0061]    In the preferred embodiment, bottom surface  60  also includes at least one, and preferably a plurality of, grooves  86  that are similar in shape and disposition to the grooves  28  described above in conjunction with FIGS. 1 and 2. Grooves  86  preferably have the “V”-shape as described above. While the grooves  86  may be located generally anywhere across the bottom surface  60 , it is preferred to locate the grooves substantially within the curved portion  62  of the bottom surface  60 . As seen in FIG. 10, grooves  68  may extend from front to back from a position on surface  60  somewhat forward of the point where front surfaces  52   a  and  52   b  interest side surfaces  54   a  and  54   b,  respectively, to a position just forward of edge  75  of gutter  74 . Care must be taken to space the grooves  86  away from edge  75  sufficiently to avoid weakening edge  75 . Grooves  86  not only result in a lighter block  50 , but also realize a cost savings in the use of less concrete to form the blocks  50 . Additionally, grooves  86  may aid installers in the field by providing a fracture line along with the block  50  may be broken to fill a gap in wall made from blocks  50 .  
         [0062]    Referring now to FIG. 17, block  110  includes a front surface  112  that comprises an outwardly curved, or curvilinear surface that is free from vertices that extend substantially from the top surface to the bottom surface, as opposed to a block having a front surface with vertices formed by facets, as depicted in FIG. 13, for example. Although the front surface  112  is depicted as having a roughened texture that approximates a split-face look, it will be appreciated that other textures are possible. Also shown in the Figure is a rear surface  116  which has a smaller width than front surface  112  such that side surface  114   a  and  114   b  converge rearwardly in order to be integral with rear surface  116 . This shape allows the construction of straight, concave, convex, or serpentine walls without interrupting the relatively uniform appearance created by the front surfaces  112  of a plurality of blocks  110  forming a wall. As will be appreciated, the curvature of the front surface  112  of the block  110  may be configured so that the front surfaces of a plurality of blocks may also form closed, substantially cylindrical structures.  
         [0063]    Although not depicted, the bottom surface of the block of this embodiment is identical to the bottom surface depicted in FIGS. 1 and 4. Thus, the bottom surface extends from front surface to rear surface  116  and from side surface  114   a  to side surface  114   b.  Bottom surface includes a non-planar portion with a plurality of upwardly extending grooves (not shown). Non-planar portion is similar to the non-planar portion  22  depicted in FIGS. 1, 3 and  4 , in that it is relatively cylindrical and extends from side surface  14   a  to side surface  14   b.  As with the non-planar portion  22  of FIGS. 1, 3, and  4 , the non-planar portion of this embodiment does not extend substantially forward of the points where side surfaces  114   a  and  114   b  intersect with the front surface  112 . This enables the non-planar portion to be substantially hidden from view in a completed wall, regardless of whether the wall is straight, concave, convex, or serpentine. Similarly, extending the non-planar portion from side surface  114   a  to side surface  114   b  creates a gap  124  between the bottom surface and the upper surface of a lower course of blocks that may also be used to facilitate manipulation of the block. Also, as shown in the Figure, non-planar portion  122  extends rearwardly towards downward projection  134 , but stops short a predetermined distance therebefore.  
         [0064]    Referring now to FIGS. 18 and 19, another embodiment shows a block  110  that includes a front surface  112  that comprises an outwardly curved, or curvilinear surface, which is free from vertices that extend substantially from the top surface to the bottom surface. The front surface  112  of this embodiment is also depicted as having a roughened texture that approximates a split-face look, but it is understood that other textures are possible. As with the embodiment as depicted in FIGS.  6 - 9 , the block of this embodiment includes a non-planar portion  122  that is substantially concave or ovate in shape, and a plurality of upwardly extending “V” shaped grooves  128  having convergent surfaces  130 ,  132 .  
         [0065]    Referring now to FIG. 20, another embodiment shows also shows a block  150  that includes a front surface  152  that comprises an outwardly curved or curvilinear surface, which is free from vertices that extend substantially from the top surface to the bottom surface, as opposed to a block having a front surface with vertices formed by facets, as depicted in FIG. 13, for example. Retaining wall block  150  also includes side surfaces  154   a  and  154   b  that extend rearwardly from front surface  152  toward rear surface  156 . Bottom surface  160  extends from front surface  152  to a gutter  174  and from side surface  154   a  to side surface  154   b.  Bottom surface  160  includes a non-planar portion  162  that is a relatively cylindrical indentation in bottom surface  160 , extending from side surface  154   a  to side surface  154   b  (See also, FIG. 23). The non-planar portion  162  is arranged so that it stops short of the front surface  152 , and preferably does not extend substantially forward of the points of intersection where side surfaces  154   a  and  154   b  meet the front surface  152 . This ensures that non-planar portion  162  is substantially hidden from view in a completed wall, regardless of whether the wall is straight, concave, convex, or serpentine.  
         [0066]    A gap  164 , formed by the non-planar portion  162 , extends all the way from a forward edge  163  to the edge  175  of gutter  174 . Thus, a block  150  in an upper course of blocks will rest upon a block  150  in a lower course of blocks upon that portion of bottom surface  160  that extends between the front surface  152  and the forward edge  163  of the non-planar portion  162 , and the edge  175  of gutter  174 .  
         [0067]    In this embodiment, bottom surface  160  also includes at least one, and preferably a plurality of, grooves  186  that are similar in shape and disposition to the grooves  28  described above in conjunction with FIGS. 1 and 2, and as depicted in FIGS. 10, 11, and  12 . Grooves  186  preferably have the “V”-shape as described above. While the grooves  186  may be located generally anywhere across the bottom surface  160 , it is preferred to locate the grooves substantially within the curved portion  162  of the bottom surface  160 . As seen in FIG. 20, grooves  168  may extend substantially from front to back from a position on surface  160  somewhat forward of the point where front surface  152  interests side surfaces  154   a  and  154   b,  respectively, to a position just forward of edge  175  of gutter  174 . Grooves  186  not only result in a lighter block  150 , but also realize a cost savings in the use of less concrete to form the blocks  150 . Additionally, grooves  186  may aid installers in the field by providing a fracture line along with the block  150  may be broken to fill a gap in wall made from blocks  150 .  
         [0068]    Block  150  also has a heel portion  170  that comprises the rear surface  182 , a projection  172  and a gutter  174 . As can be seen more clearly in FIG. 21, sides  154   a  and  154   b  incorporate shoulders  176   a  and  176   b,  respectively. Shoulders  176  may also be seen as a forward boundary of the heel portion  170  of the block  150 . Note that shoulders  176  form an obtuse angle with respect to sides  154 . Heel portion side walls  178   a  and  178   b  extend rearwardly from respective shoulders  176   a  and  176   b  and intersect with rear surface  156  of block  150 . Heel portion side walls  178   a  and  178   b  are preferably formed perpendicular to shoulders  176   a  and  176   b  and to rear surface  156  of block  150 . The resulting sides  154  comprise multiple facets and provide a number of benefits. Formation of side walls  178   a  and  178   b  as illustrated in the Figures results in a lighter block  150  as the block  150  will have a smaller volume.  
         [0069]    Referring now to FIG. 21, top surface  158  is generally planar and continuous across its extents. Top surface  158  extends from side surface  154   a  to side surface  154   b,  and from front surface  152  to rear surface  156 . Preferably, top surface  158  is generally perpendicular to side surfaces  154   a  and  154   b,  and also to front surface  152  and rear surface  156 . As can be seen in the Figures, rear surface  156  has a smaller width than front surface  152 . Side surfaces  154   a  and  154   b  converge rearwardly toward the rear surface  156  at obtuse angle to the rear surface  156   
         [0070]    Referring now to FIG. 22, the front surface  152  comprises a curvilinear surface that may be curved outwardly. This curvature enables blocks  152  to form wall structures that are substantially cylindrical. Although a relatively shallow arc that extends between the sides  154   a,    154   b  is depicted, it will be appreciated that front surface  152  may be formed in different arcs, for example, a hemispherical arc. Moreover, the arced front surface  152  may be oriented so that it extends between the top and bottom surfaces  158 ,  160 , or comprises a series of curvilinear surfaces in a scallop-like configuration.  
         [0071]    Referring now to FIG. 23, gap  164  between adjacent courses of blocks  150  can be more easily seen. As with the previous embodiments, gap  164  may be used to facilitate manipulation of blocks  150 . As can be appreciated, the rear of the block  150  is supported only on edge  175  and not on a planar surface. This minimizes the surface area supporting the rear of the block  150  and reduces the effects of extraneous material such as rocks, sand, or bits of concrete that may be present on the upper surface  158  of a lower course of blocks.  
         [0072]    Gutter  174  has a generally “U” shaped cross-sectional area that extends upwardly from edge  175  into the body of block  150  and laterally between heel portion side walls  178   a  and  178   b.  As will be appreciated, the exact cross-sectional shape of the gutter  176  may vary. The rear face of the gutter  174  extends downwardly, away from the top surface of block  150  and beyond edge  175  to form an abutting surface  180  of projection  172 . Projection  172  and its abutting surface  180  functions in the same manner as projection  34  and its abutting surface  36 , described above. Projection  172  is preferably offset forwardly from the rear surface  156 . As can be seen in the Figures, rear face  182  of projection  172  is moved forward of the rear surface  156  of the block  150  so that the projection  172  is generally intermediate or interposed between the rear surface  156  and the rear edge  175  of the non-planar portion  162 . The positioning of the projection  172  away from the rear surface has an advantage in that it is less likely to be chipped and fractured while the block is being manipulated and positioned. In other words, it is in a location that offers greater protection. Note that the abutting surface  180  and the rear face  182  of projection  172  are canted towards each other so that the projection  172  has a generally trapezoidal cross-sectional shape. The trapezoidal shape of the projection  172  aids in the rapid construction of walls by preventing the entrapment of sand, gravel, or pieces of concrete between the abutting surface  180  of a block  150  in an upper course and the rear surface  156  a block  150  in a lower course.  
         [0073]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.

Summary:
A block for use in constructing a multiple course retaining wall. The block has a substantially planar top surface, a front surface, wherein said front surface is of a substantially curvilinear shape, a rear surface, opposed side surfaces, and a bottom surface. The bottom surface has a predetermined area and a non-planar portion, with the non-planar portion comprising a continuous area making up at least one-quarter of the bottom surface and creating a cavity between the bottom surface of the block and a top surface of a lower course of blocks when the block is placed on the top surface of the lower course of blocks. The cavity allows dirt and other foreign matter to exist between successive courses of blocks without creating instability between the block and the lower course of blocks.